Prototype: phased shutdown for MTP (#5345) by Evangelink · Pull Request #8580 · microsoft/testfx

Amaury Levé (Evangelink) · 2026-05-25T20:52:52Z

Summary

Prototype of a two-phase graceful shutdown for Microsoft.Testing.Platform, exploring the design discussed in #5345 (see this comment).

Status: draft / RFC — opened for early design feedback. CLI options and most consumer migrations are intentionally deferred.

Motivation

Today MTP exposes a single ITestApplicationCancellationTokenSource.CancellationToken. On Ctrl+C, every consumer (tests, extensions, hosts) receives the same signal at the same time, and there is no contract distinguishing "please wind down gracefully" from "stop right now". This conflates the two shutdown modes that virtually every other host-style runtime treats as distinct phases (systemd EXTEND_TIMEOUT_USEC, macOS NSTerminateLater, AWS Lambda Extensions SHUTDOWN, Kubernetes preStop / terminationGracePeriodSeconds, docker compose 2-press SIGTERM→SIGKILL, Vitest teardownTimeout, …).

What's in this PR

A working prototype of Design A from the offline analysis:

Concept	Implementation
Two cancellation tokens	`DrainingToken` (graceful) and `AbortingToken` (forceful) on the internal `ITestApplicationCancellationTokenSource`
Back-compat	Existing `CancellationToken` is preserved as an alias of `DrainingToken` so the ~14 current consumers keep working unchanged
`Abort()` API	Explicit programmatic escalation entry point
State machine	`Running → Draining → Aborting` using `Interlocked.CompareExchange` for atomic phase transitions
Ctrl+C UX (matches docker compose / kubectl / npm)	1st press → Draining (+ 30s grace timer); 2nd press → Aborting (+ 10s abort-timeout FailFast safety net); 3rd press → not intercepted, runtime kills the process
Auto-escalation	Grace-period timer escalates Draining → Aborting if drain takes too long
Last-resort	Abort-timeout uses `IEnvironment.FailFast` (banned `Environment.FailFast` replaced with the injectable wrapper)

Files

src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs — extended interface
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs — full rewrite
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs — inline mock updated
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs — 6 new unit tests

Verification

Builds clean on net8.0 / net9.0 / netstandard2.0
6/6 new tests pass on net9.0
6/6 new tests pass on net462 (confirms no DIM/runtime issues for the MSTest.TestAdapter consumer of the netstandard2.0 build)
24/24 adjacent CommonHost / Cancellation / StopPolic* tests still pass — no regressions

Intentionally deferred (follow-ups)

To keep this PR reviewable, the following are explicitly NOT in scope and will land as separate PRs once the core direction is approved:

CLI options --shutdown-grace-period and --shutdown-abort-timeout via PlatformCommandLineProvider + HelpInfoTests acceptance assertions
Environment-variable propagation to TestHostOrchestratorHost / TestHostControllersTestHost controlled children
TerminalOutputDevice UX line: "Cancelling test session… (press Ctrl+C again to force quit)"
Migrating existing token consumers from the legacy alias onto explicit DrainingToken / AbortingToken usage
Coordinating with the HotReload extension's own CancelKeyPress handler
Design B (IShutdownParticipant ack/extend protocol) — separate RFC

Open design questions

Should defaults be 30s/10s or come from HostOptions.ShutdownTimeout + a new AbortTimeout?
Should the IEnvironment injection be threaded explicitly from TestHostBuilder.CommonServices now, or stay defaulted to SystemEnvironment?
Are we happy with letting the 3rd Ctrl+C reach the runtime, or should we still Process.Kill ourselves?

Full RFC (motivation, prior-art table, rollout plan, alternatives) is available in my session notes and will be posted as a comment on #5345 once the prototype direction is acknowledged.

Refs #5345

Introduce a two-phase shutdown model for Microsoft.Testing.Platform so test sessions get a deterministic drain window before being aborted: - Extend internal ITestApplicationCancellationTokenSource with DrainingToken (graceful cancel) and AbortingToken (forceful abort), plus an Abort() entry point. The existing CancellationToken is kept as a back-compat alias for DrainingToken so current consumers keep observing graceful cancellation without changes. - Rewrite CTRLPlusCCancellationTokenSource with a Running -> Draining -> Aborting state machine: * 1st Ctrl+C enters Draining, starts a 30s grace timer that escalates to Aborting on elapse. * 2nd Ctrl+C escalates to Aborting immediately, starts a 10s abort-timeout safety net that FailFasts via IEnvironment. * 3rd Ctrl+C is no longer intercepted - the runtime terminates the process (matches docker compose / kubectl / npm UX). - Add 6 unit tests covering initial state, single/idempotent cancel, abort, grace-period escalation, and zero-grace escalation. Passes on net9.0 and net462. CLI options (--shutdown-grace-period, --shutdown-abort-timeout), env- var propagation to controlled hosts, TerminalOutputDevice UX updates, and migration of existing token consumers are intentionally deferred to follow-up PRs and tracked in the RFC. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Prototype implementation of a two-phase shutdown model for Microsoft.Testing.Platform (MTP), introducing distinct “Draining” vs “Aborting” cancellation semantics to address Ctrl+C behavior discussed in #5345 while keeping back-compat for existing token consumers.

Changes:

Extend ITestApplicationCancellationTokenSource with DrainingToken, AbortingToken, and an Abort() escalation API (with CancellationToken preserved as a Draining alias).
Rewrite CTRLPlusCCancellationTokenSource to implement a Running → Draining → Aborting phase model with Ctrl+C escalation and grace/abort timers.
Add unit tests covering the new phase/token behavior.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs	Adds two-phase shutdown tokens and `Abort()` API while preserving legacy token alias.
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs	Implements the phased shutdown state machine, Ctrl+C escalation logic, and timers.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs	Updates local test stub to satisfy the extended cancellation token source interface.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs	Adds new unit tests validating draining/aborting semantics and grace escalation.

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 5

When the test-application cancellation token is signalled and shutdown takes longer than expected, MTP now periodically prints a 'Still waiting for: ...' warning listing the extensions and consumers that have not yet returned. This makes a hanging Ctrl+C observable without users having to inspect the process state. Adds a new internal IShutdownProgressReporter service plus a default ShutdownProgressReporter implementation. The reporter wraps the three known blocking await sites: * ITestSessionLifetimeHandler.OnTestSessionFinishingAsync (both non-consumer and consumer passes in CommonTestHost) * IAsyncConsumerDataProcessor.DrainDataAsync per consumer in AsynchronousMessageBus The watchdog only starts after the cancellation token fires, waits a quiet window (3s) to avoid noise on clean shutdowns, then polls every second. Output goes through IOutputDevice as a WarningMessageOutputDeviceData. Refs #5345. Complementary to #8580 - the same trackers will feed the eventual `force-killed because X didn't drain` message once the phased-shutdown RFC lands. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Dispose() now detaches the Console.CancelKeyPress handler and disposes any pending escalation CancellationTokenSources so callbacks don't fire after the source is disposed and we don't keep the instance alive through the static console event. - OnConsoleCancelKeyPressed guards against post-Dispose invocations and routes the 2nd Ctrl+C through Abort() rather than EnterAborting() directly, keeping the Running -> Draining -> Aborting invariant. - EnterAborting() now calls EnterDraining() first so the legacy CancellationToken / DrainingToken are always signaled when AbortingToken is canceled, and uses CompareExchange(Draining -> Aborting) instead of an unconditional Exchange. - ScheduleEscalation retains the timer CancellationTokenSource so it can be disposed in Dispose(). - Test GracePeriodElapse_EscalatesToAborting is now event-driven via a TaskCompletionSource registered on AbortingToken (no more Task.Delay polling loop). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-06-05T12:14:12Z

Copilot resolve the merge conflicts in this pull request

…ased-shutdown # Conflicts: # src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs # test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>

Copilot · 2026-06-05T12:23:27Z

Copilot resolve the merge conflicts in this pull request

Done. Merged origin/main into this branch (commit 069d9ad). The two conflicts were in:

CTRLPlusCCancellationTokenSource.cs — resolved by keeping our two-phase implementation
CTRLPlusCCancellationTokenSourceTests.cs — resolved by keeping our phased-shutdown tests

Add coverage for Console.CancelKeyPress unsubscription and keep the phase field mutable while using the newer Lock type where available. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 3

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-05-25T20:52:52Z

Summary

Prototype of a two-phase graceful shutdown for Microsoft.Testing.Platform, exploring the design discussed in #5345 (see this comment).

Status: draft / RFC — opened for early design feedback. CLI options and most consumer migrations are intentionally deferred.

Motivation

Today MTP exposes a single ITestApplicationCancellationTokenSource.CancellationToken. On Ctrl+C, every consumer (tests, extensions, hosts) receives the same signal at the same time, and there is no contract distinguishing "please wind down gracefully" from "stop right now". This conflates the two shutdown modes that virtually every other host-style runtime treats as distinct phases (systemd EXTEND_TIMEOUT_USEC, macOS NSTerminateLater, AWS Lambda Extensions SHUTDOWN, Kubernetes preStop / terminationGracePeriodSeconds, docker compose 2-press SIGTERM→SIGKILL, Vitest teardownTimeout, …).

What's in this PR

A working prototype of Design A from the offline analysis:

Concept	Implementation
Two cancellation tokens	`DrainingToken` (graceful) and `AbortingToken` (forceful) on the internal `ITestApplicationCancellationTokenSource`
Back-compat	Existing `CancellationToken` is preserved as an alias of `DrainingToken` so the ~14 current consumers keep working unchanged
`Abort()` API	Explicit programmatic escalation entry point
State machine	`Running → Draining → Aborting` using `Interlocked.CompareExchange` for atomic phase transitions
Ctrl+C UX (matches docker compose / kubectl / npm)	1st press → Draining (+ 30s grace timer); 2nd press → Aborting (+ 10s abort-timeout FailFast safety net); 3rd press → not intercepted, runtime kills the process
Auto-escalation	Grace-period timer escalates Draining → Aborting if drain takes too long
Last-resort	Abort-timeout uses `IEnvironment.FailFast` (banned `Environment.FailFast` replaced with the injectable wrapper)

Files

src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs — extended interface
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs — full rewrite
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs — inline mock updated
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs — 6 new unit tests

Verification

Builds clean on net8.0 / net9.0 / netstandard2.0
6/6 new tests pass on net9.0
6/6 new tests pass on net462 (confirms no DIM/runtime issues for the MSTest.TestAdapter consumer of the netstandard2.0 build)
24/24 adjacent CommonHost / Cancellation / StopPolic* tests still pass — no regressions

Intentionally deferred (follow-ups)

To keep this PR reviewable, the following are explicitly NOT in scope and will land as separate PRs once the core direction is approved:

CLI options --shutdown-grace-period and --shutdown-abort-timeout via PlatformCommandLineProvider + HelpInfoTests acceptance assertions
Environment-variable propagation to TestHostOrchestratorHost / TestHostControllersTestHost controlled children
TerminalOutputDevice UX line: "Cancelling test session… (press Ctrl+C again to force quit)"
Migrating existing token consumers from the legacy alias onto explicit DrainingToken / AbortingToken usage
Coordinating with the HotReload extension's own CancelKeyPress handler
Design B (IShutdownParticipant ack/extend protocol) — separate RFC

Open design questions

Should defaults be 30s/10s or come from HostOptions.ShutdownTimeout + a new AbortTimeout?
Should the IEnvironment injection be threaded explicitly from TestHostBuilder.CommonServices now, or stay defaulted to SystemEnvironment?
Are we happy with letting the 3rd Ctrl+C reach the runtime, or should we still Process.Kill ourselves?

Full RFC (motivation, prior-art table, rollout plan, alternatives) is available in my session notes and will be posted as a comment on #5345 once the prototype direction is acknowledged.

Refs #5345

Introduce a two-phase shutdown model for Microsoft.Testing.Platform so test sessions get a deterministic drain window before being aborted: - Extend internal ITestApplicationCancellationTokenSource with DrainingToken (graceful cancel) and AbortingToken (forceful abort), plus an Abort() entry point. The existing CancellationToken is kept as a back-compat alias for DrainingToken so current consumers keep observing graceful cancellation without changes. - Rewrite CTRLPlusCCancellationTokenSource with a Running -> Draining -> Aborting state machine: * 1st Ctrl+C enters Draining, starts a 30s grace timer that escalates to Aborting on elapse. * 2nd Ctrl+C escalates to Aborting immediately, starts a 10s abort-timeout safety net that FailFasts via IEnvironment. * 3rd Ctrl+C is no longer intercepted - the runtime terminates the process (matches docker compose / kubectl / npm UX). - Add 6 unit tests covering initial state, single/idempotent cancel, abort, grace-period escalation, and zero-grace escalation. Passes on net9.0 and net462. CLI options (--shutdown-grace-period, --shutdown-abort-timeout), env- var propagation to controlled hosts, TerminalOutputDevice UX updates, and migration of existing token consumers are intentionally deferred to follow-up PRs and tracked in the RFC. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Prototype implementation of a two-phase shutdown model for Microsoft.Testing.Platform (MTP), introducing distinct “Draining” vs “Aborting” cancellation semantics to address Ctrl+C behavior discussed in #5345 while keeping back-compat for existing token consumers.

Changes:

Extend ITestApplicationCancellationTokenSource with DrainingToken, AbortingToken, and an Abort() escalation API (with CancellationToken preserved as a Draining alias).
Rewrite CTRLPlusCCancellationTokenSource to implement a Running → Draining → Aborting phase model with Ctrl+C escalation and grace/abort timers.
Add unit tests covering the new phase/token behavior.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs	Adds two-phase shutdown tokens and `Abort()` API while preserving legacy token alias.
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs	Implements the phased shutdown state machine, Ctrl+C escalation logic, and timers.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs	Updates local test stub to satisfy the extended cancellation token source interface.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs	Adds new unit tests validating draining/aborting semantics and grace escalation.

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 5

When the test-application cancellation token is signalled and shutdown takes longer than expected, MTP now periodically prints a 'Still waiting for: ...' warning listing the extensions and consumers that have not yet returned. This makes a hanging Ctrl+C observable without users having to inspect the process state. Adds a new internal IShutdownProgressReporter service plus a default ShutdownProgressReporter implementation. The reporter wraps the three known blocking await sites: * ITestSessionLifetimeHandler.OnTestSessionFinishingAsync (both non-consumer and consumer passes in CommonTestHost) * IAsyncConsumerDataProcessor.DrainDataAsync per consumer in AsynchronousMessageBus The watchdog only starts after the cancellation token fires, waits a quiet window (3s) to avoid noise on clean shutdowns, then polls every second. Output goes through IOutputDevice as a WarningMessageOutputDeviceData. Refs #5345. Complementary to #8580 - the same trackers will feed the eventual `force-killed because X didn't drain` message once the phased-shutdown RFC lands. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Dispose() now detaches the Console.CancelKeyPress handler and disposes any pending escalation CancellationTokenSources so callbacks don't fire after the source is disposed and we don't keep the instance alive through the static console event. - OnConsoleCancelKeyPressed guards against post-Dispose invocations and routes the 2nd Ctrl+C through Abort() rather than EnterAborting() directly, keeping the Running -> Draining -> Aborting invariant. - EnterAborting() now calls EnterDraining() first so the legacy CancellationToken / DrainingToken are always signaled when AbortingToken is canceled, and uses CompareExchange(Draining -> Aborting) instead of an unconditional Exchange. - ScheduleEscalation retains the timer CancellationTokenSource so it can be disposed in Dispose(). - Test GracePeriodElapse_EscalatesToAborting is now event-driven via a TaskCompletionSource registered on AbortingToken (no more Task.Delay polling loop). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-06-05T12:14:12Z

Copilot resolve the merge conflicts in this pull request

…ased-shutdown # Conflicts: # src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs # test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>

Copilot · 2026-06-05T12:23:27Z

Copilot resolve the merge conflicts in this pull request

Done. Merged origin/main into this branch (commit 069d9ad). The two conflicts were in:

CTRLPlusCCancellationTokenSource.cs — resolved by keeping our two-phase implementation
CTRLPlusCCancellationTokenSourceTests.cs — resolved by keeping our phased-shutdown tests

Add coverage for Console.CancelKeyPress unsubscription and keep the phase field mutable while using the newer Lock type where available. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 3

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-05-25T20:52:52Z

Summary

Prototype of a two-phase graceful shutdown for Microsoft.Testing.Platform, exploring the design discussed in #5345 (see this comment).

Status: draft / RFC — opened for early design feedback. CLI options and most consumer migrations are intentionally deferred.

Motivation

Today MTP exposes a single ITestApplicationCancellationTokenSource.CancellationToken. On Ctrl+C, every consumer (tests, extensions, hosts) receives the same signal at the same time, and there is no contract distinguishing "please wind down gracefully" from "stop right now". This conflates the two shutdown modes that virtually every other host-style runtime treats as distinct phases (systemd EXTEND_TIMEOUT_USEC, macOS NSTerminateLater, AWS Lambda Extensions SHUTDOWN, Kubernetes preStop / terminationGracePeriodSeconds, docker compose 2-press SIGTERM→SIGKILL, Vitest teardownTimeout, …).

What's in this PR

A working prototype of Design A from the offline analysis:

Concept	Implementation
Two cancellation tokens	`DrainingToken` (graceful) and `AbortingToken` (forceful) on the internal `ITestApplicationCancellationTokenSource`
Back-compat	Existing `CancellationToken` is preserved as an alias of `DrainingToken` so the ~14 current consumers keep working unchanged
`Abort()` API	Explicit programmatic escalation entry point
State machine	`Running → Draining → Aborting` using `Interlocked.CompareExchange` for atomic phase transitions
Ctrl+C UX (matches docker compose / kubectl / npm)	1st press → Draining (+ 30s grace timer); 2nd press → Aborting (+ 10s abort-timeout FailFast safety net); 3rd press → not intercepted, runtime kills the process
Auto-escalation	Grace-period timer escalates Draining → Aborting if drain takes too long
Last-resort	Abort-timeout uses `IEnvironment.FailFast` (banned `Environment.FailFast` replaced with the injectable wrapper)

Files

src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs — extended interface
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs — full rewrite
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs — inline mock updated
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs — 6 new unit tests

Verification

Builds clean on net8.0 / net9.0 / netstandard2.0
6/6 new tests pass on net9.0
6/6 new tests pass on net462 (confirms no DIM/runtime issues for the MSTest.TestAdapter consumer of the netstandard2.0 build)
24/24 adjacent CommonHost / Cancellation / StopPolic* tests still pass — no regressions

Intentionally deferred (follow-ups)

To keep this PR reviewable, the following are explicitly NOT in scope and will land as separate PRs once the core direction is approved:

CLI options --shutdown-grace-period and --shutdown-abort-timeout via PlatformCommandLineProvider + HelpInfoTests acceptance assertions
Environment-variable propagation to TestHostOrchestratorHost / TestHostControllersTestHost controlled children
TerminalOutputDevice UX line: "Cancelling test session… (press Ctrl+C again to force quit)"
Migrating existing token consumers from the legacy alias onto explicit DrainingToken / AbortingToken usage
Coordinating with the HotReload extension's own CancelKeyPress handler
Design B (IShutdownParticipant ack/extend protocol) — separate RFC

Open design questions

Should defaults be 30s/10s or come from HostOptions.ShutdownTimeout + a new AbortTimeout?
Should the IEnvironment injection be threaded explicitly from TestHostBuilder.CommonServices now, or stay defaulted to SystemEnvironment?
Are we happy with letting the 3rd Ctrl+C reach the runtime, or should we still Process.Kill ourselves?

Full RFC (motivation, prior-art table, rollout plan, alternatives) is available in my session notes and will be posted as a comment on #5345 once the prototype direction is acknowledged.

Refs #5345

Introduce a two-phase shutdown model for Microsoft.Testing.Platform so test sessions get a deterministic drain window before being aborted: - Extend internal ITestApplicationCancellationTokenSource with DrainingToken (graceful cancel) and AbortingToken (forceful abort), plus an Abort() entry point. The existing CancellationToken is kept as a back-compat alias for DrainingToken so current consumers keep observing graceful cancellation without changes. - Rewrite CTRLPlusCCancellationTokenSource with a Running -> Draining -> Aborting state machine: * 1st Ctrl+C enters Draining, starts a 30s grace timer that escalates to Aborting on elapse. * 2nd Ctrl+C escalates to Aborting immediately, starts a 10s abort-timeout safety net that FailFasts via IEnvironment. * 3rd Ctrl+C is no longer intercepted - the runtime terminates the process (matches docker compose / kubectl / npm UX). - Add 6 unit tests covering initial state, single/idempotent cancel, abort, grace-period escalation, and zero-grace escalation. Passes on net9.0 and net462. CLI options (--shutdown-grace-period, --shutdown-abort-timeout), env- var propagation to controlled hosts, TerminalOutputDevice UX updates, and migration of existing token consumers are intentionally deferred to follow-up PRs and tracked in the RFC. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Prototype implementation of a two-phase shutdown model for Microsoft.Testing.Platform (MTP), introducing distinct “Draining” vs “Aborting” cancellation semantics to address Ctrl+C behavior discussed in #5345 while keeping back-compat for existing token consumers.

Changes:

Extend ITestApplicationCancellationTokenSource with DrainingToken, AbortingToken, and an Abort() escalation API (with CancellationToken preserved as a Draining alias).
Rewrite CTRLPlusCCancellationTokenSource to implement a Running → Draining → Aborting phase model with Ctrl+C escalation and grace/abort timers.
Add unit tests covering the new phase/token behavior.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs	Adds two-phase shutdown tokens and `Abort()` API while preserving legacy token alias.
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs	Implements the phased shutdown state machine, Ctrl+C escalation logic, and timers.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs	Updates local test stub to satisfy the extended cancellation token source interface.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs	Adds new unit tests validating draining/aborting semantics and grace escalation.

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 5

When the test-application cancellation token is signalled and shutdown takes longer than expected, MTP now periodically prints a 'Still waiting for: ...' warning listing the extensions and consumers that have not yet returned. This makes a hanging Ctrl+C observable without users having to inspect the process state. Adds a new internal IShutdownProgressReporter service plus a default ShutdownProgressReporter implementation. The reporter wraps the three known blocking await sites: * ITestSessionLifetimeHandler.OnTestSessionFinishingAsync (both non-consumer and consumer passes in CommonTestHost) * IAsyncConsumerDataProcessor.DrainDataAsync per consumer in AsynchronousMessageBus The watchdog only starts after the cancellation token fires, waits a quiet window (3s) to avoid noise on clean shutdowns, then polls every second. Output goes through IOutputDevice as a WarningMessageOutputDeviceData. Refs #5345. Complementary to #8580 - the same trackers will feed the eventual `force-killed because X didn't drain` message once the phased-shutdown RFC lands. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Dispose() now detaches the Console.CancelKeyPress handler and disposes any pending escalation CancellationTokenSources so callbacks don't fire after the source is disposed and we don't keep the instance alive through the static console event. - OnConsoleCancelKeyPressed guards against post-Dispose invocations and routes the 2nd Ctrl+C through Abort() rather than EnterAborting() directly, keeping the Running -> Draining -> Aborting invariant. - EnterAborting() now calls EnterDraining() first so the legacy CancellationToken / DrainingToken are always signaled when AbortingToken is canceled, and uses CompareExchange(Draining -> Aborting) instead of an unconditional Exchange. - ScheduleEscalation retains the timer CancellationTokenSource so it can be disposed in Dispose(). - Test GracePeriodElapse_EscalatesToAborting is now event-driven via a TaskCompletionSource registered on AbortingToken (no more Task.Delay polling loop). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-06-05T12:14:12Z

Copilot resolve the merge conflicts in this pull request

…ased-shutdown # Conflicts: # src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs # test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>

Copilot · 2026-06-05T12:23:27Z

Copilot resolve the merge conflicts in this pull request

Done. Merged origin/main into this branch (commit 069d9ad). The two conflicts were in:

CTRLPlusCCancellationTokenSource.cs — resolved by keeping our two-phase implementation
CTRLPlusCCancellationTokenSourceTests.cs — resolved by keeping our phased-shutdown tests

Add coverage for Console.CancelKeyPress unsubscription and keep the phase field mutable while using the newer Lock type where available. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 3

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-05-25T20:52:52Z

Summary

Prototype of a two-phase graceful shutdown for Microsoft.Testing.Platform, exploring the design discussed in #5345 (see this comment).

Status: draft / RFC — opened for early design feedback. CLI options and most consumer migrations are intentionally deferred.

Motivation

Today MTP exposes a single ITestApplicationCancellationTokenSource.CancellationToken. On Ctrl+C, every consumer (tests, extensions, hosts) receives the same signal at the same time, and there is no contract distinguishing "please wind down gracefully" from "stop right now". This conflates the two shutdown modes that virtually every other host-style runtime treats as distinct phases (systemd EXTEND_TIMEOUT_USEC, macOS NSTerminateLater, AWS Lambda Extensions SHUTDOWN, Kubernetes preStop / terminationGracePeriodSeconds, docker compose 2-press SIGTERM→SIGKILL, Vitest teardownTimeout, …).

What's in this PR

A working prototype of Design A from the offline analysis:

Concept	Implementation
Two cancellation tokens	`DrainingToken` (graceful) and `AbortingToken` (forceful) on the internal `ITestApplicationCancellationTokenSource`
Back-compat	Existing `CancellationToken` is preserved as an alias of `DrainingToken` so the ~14 current consumers keep working unchanged
`Abort()` API	Explicit programmatic escalation entry point
State machine	`Running → Draining → Aborting` using `Interlocked.CompareExchange` for atomic phase transitions
Ctrl+C UX (matches docker compose / kubectl / npm)	1st press → Draining (+ 30s grace timer); 2nd press → Aborting (+ 10s abort-timeout FailFast safety net); 3rd press → not intercepted, runtime kills the process
Auto-escalation	Grace-period timer escalates Draining → Aborting if drain takes too long
Last-resort	Abort-timeout uses `IEnvironment.FailFast` (banned `Environment.FailFast` replaced with the injectable wrapper)

Files

src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs — extended interface
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs — full rewrite
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs — inline mock updated
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs — 6 new unit tests

Verification

Builds clean on net8.0 / net9.0 / netstandard2.0
6/6 new tests pass on net9.0
6/6 new tests pass on net462 (confirms no DIM/runtime issues for the MSTest.TestAdapter consumer of the netstandard2.0 build)
24/24 adjacent CommonHost / Cancellation / StopPolic* tests still pass — no regressions

Intentionally deferred (follow-ups)

To keep this PR reviewable, the following are explicitly NOT in scope and will land as separate PRs once the core direction is approved:

CLI options --shutdown-grace-period and --shutdown-abort-timeout via PlatformCommandLineProvider + HelpInfoTests acceptance assertions
Environment-variable propagation to TestHostOrchestratorHost / TestHostControllersTestHost controlled children
TerminalOutputDevice UX line: "Cancelling test session… (press Ctrl+C again to force quit)"
Migrating existing token consumers from the legacy alias onto explicit DrainingToken / AbortingToken usage
Coordinating with the HotReload extension's own CancelKeyPress handler
Design B (IShutdownParticipant ack/extend protocol) — separate RFC

Open design questions

Should defaults be 30s/10s or come from HostOptions.ShutdownTimeout + a new AbortTimeout?
Should the IEnvironment injection be threaded explicitly from TestHostBuilder.CommonServices now, or stay defaulted to SystemEnvironment?
Are we happy with letting the 3rd Ctrl+C reach the runtime, or should we still Process.Kill ourselves?

Full RFC (motivation, prior-art table, rollout plan, alternatives) is available in my session notes and will be posted as a comment on #5345 once the prototype direction is acknowledged.

Refs #5345

Introduce a two-phase shutdown model for Microsoft.Testing.Platform so test sessions get a deterministic drain window before being aborted: - Extend internal ITestApplicationCancellationTokenSource with DrainingToken (graceful cancel) and AbortingToken (forceful abort), plus an Abort() entry point. The existing CancellationToken is kept as a back-compat alias for DrainingToken so current consumers keep observing graceful cancellation without changes. - Rewrite CTRLPlusCCancellationTokenSource with a Running -> Draining -> Aborting state machine: * 1st Ctrl+C enters Draining, starts a 30s grace timer that escalates to Aborting on elapse. * 2nd Ctrl+C escalates to Aborting immediately, starts a 10s abort-timeout safety net that FailFasts via IEnvironment. * 3rd Ctrl+C is no longer intercepted - the runtime terminates the process (matches docker compose / kubectl / npm UX). - Add 6 unit tests covering initial state, single/idempotent cancel, abort, grace-period escalation, and zero-grace escalation. Passes on net9.0 and net462. CLI options (--shutdown-grace-period, --shutdown-abort-timeout), env- var propagation to controlled hosts, TerminalOutputDevice UX updates, and migration of existing token consumers are intentionally deferred to follow-up PRs and tracked in the RFC. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Prototype implementation of a two-phase shutdown model for Microsoft.Testing.Platform (MTP), introducing distinct “Draining” vs “Aborting” cancellation semantics to address Ctrl+C behavior discussed in #5345 while keeping back-compat for existing token consumers.

Changes:

Extend ITestApplicationCancellationTokenSource with DrainingToken, AbortingToken, and an Abort() escalation API (with CancellationToken preserved as a Draining alias).
Rewrite CTRLPlusCCancellationTokenSource to implement a Running → Draining → Aborting phase model with Ctrl+C escalation and grace/abort timers.
Add unit tests covering the new phase/token behavior.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs	Adds two-phase shutdown tokens and `Abort()` API while preserving legacy token alias.
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs	Implements the phased shutdown state machine, Ctrl+C escalation logic, and timers.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs	Updates local test stub to satisfy the extended cancellation token source interface.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs	Adds new unit tests validating draining/aborting semantics and grace escalation.

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 5

When the test-application cancellation token is signalled and shutdown takes longer than expected, MTP now periodically prints a 'Still waiting for: ...' warning listing the extensions and consumers that have not yet returned. This makes a hanging Ctrl+C observable without users having to inspect the process state. Adds a new internal IShutdownProgressReporter service plus a default ShutdownProgressReporter implementation. The reporter wraps the three known blocking await sites: * ITestSessionLifetimeHandler.OnTestSessionFinishingAsync (both non-consumer and consumer passes in CommonTestHost) * IAsyncConsumerDataProcessor.DrainDataAsync per consumer in AsynchronousMessageBus The watchdog only starts after the cancellation token fires, waits a quiet window (3s) to avoid noise on clean shutdowns, then polls every second. Output goes through IOutputDevice as a WarningMessageOutputDeviceData. Refs #5345. Complementary to #8580 - the same trackers will feed the eventual `force-killed because X didn't drain` message once the phased-shutdown RFC lands. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Dispose() now detaches the Console.CancelKeyPress handler and disposes any pending escalation CancellationTokenSources so callbacks don't fire after the source is disposed and we don't keep the instance alive through the static console event. - OnConsoleCancelKeyPressed guards against post-Dispose invocations and routes the 2nd Ctrl+C through Abort() rather than EnterAborting() directly, keeping the Running -> Draining -> Aborting invariant. - EnterAborting() now calls EnterDraining() first so the legacy CancellationToken / DrainingToken are always signaled when AbortingToken is canceled, and uses CompareExchange(Draining -> Aborting) instead of an unconditional Exchange. - ScheduleEscalation retains the timer CancellationTokenSource so it can be disposed in Dispose(). - Test GracePeriodElapse_EscalatesToAborting is now event-driven via a TaskCompletionSource registered on AbortingToken (no more Task.Delay polling loop). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-06-05T12:14:12Z

Copilot resolve the merge conflicts in this pull request

…ased-shutdown # Conflicts: # src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs # test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>

Copilot · 2026-06-05T12:23:27Z

Copilot resolve the merge conflicts in this pull request

Done. Merged origin/main into this branch (commit 069d9ad). The two conflicts were in:

CTRLPlusCCancellationTokenSource.cs — resolved by keeping our two-phase implementation
CTRLPlusCCancellationTokenSourceTests.cs — resolved by keeping our phased-shutdown tests

Add coverage for Console.CancelKeyPress unsubscription and keep the phase field mutable while using the newer Lock type where available. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 3

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-05-25T20:52:52Z

Summary

Prototype of a two-phase graceful shutdown for Microsoft.Testing.Platform, exploring the design discussed in #5345 (see this comment).

Status: draft / RFC — opened for early design feedback. CLI options and most consumer migrations are intentionally deferred.

Motivation

Today MTP exposes a single ITestApplicationCancellationTokenSource.CancellationToken. On Ctrl+C, every consumer (tests, extensions, hosts) receives the same signal at the same time, and there is no contract distinguishing "please wind down gracefully" from "stop right now". This conflates the two shutdown modes that virtually every other host-style runtime treats as distinct phases (systemd EXTEND_TIMEOUT_USEC, macOS NSTerminateLater, AWS Lambda Extensions SHUTDOWN, Kubernetes preStop / terminationGracePeriodSeconds, docker compose 2-press SIGTERM→SIGKILL, Vitest teardownTimeout, …).

What's in this PR

A working prototype of Design A from the offline analysis:

Concept	Implementation
Two cancellation tokens	`DrainingToken` (graceful) and `AbortingToken` (forceful) on the internal `ITestApplicationCancellationTokenSource`
Back-compat	Existing `CancellationToken` is preserved as an alias of `DrainingToken` so the ~14 current consumers keep working unchanged
`Abort()` API	Explicit programmatic escalation entry point
State machine	`Running → Draining → Aborting` using `Interlocked.CompareExchange` for atomic phase transitions
Ctrl+C UX (matches docker compose / kubectl / npm)	1st press → Draining (+ 30s grace timer); 2nd press → Aborting (+ 10s abort-timeout FailFast safety net); 3rd press → not intercepted, runtime kills the process
Auto-escalation	Grace-period timer escalates Draining → Aborting if drain takes too long
Last-resort	Abort-timeout uses `IEnvironment.FailFast` (banned `Environment.FailFast` replaced with the injectable wrapper)

Files

src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs — extended interface
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs — full rewrite
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs — inline mock updated
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs — 6 new unit tests

Verification

Builds clean on net8.0 / net9.0 / netstandard2.0
6/6 new tests pass on net9.0
6/6 new tests pass on net462 (confirms no DIM/runtime issues for the MSTest.TestAdapter consumer of the netstandard2.0 build)
24/24 adjacent CommonHost / Cancellation / StopPolic* tests still pass — no regressions

Intentionally deferred (follow-ups)

To keep this PR reviewable, the following are explicitly NOT in scope and will land as separate PRs once the core direction is approved:

CLI options --shutdown-grace-period and --shutdown-abort-timeout via PlatformCommandLineProvider + HelpInfoTests acceptance assertions
Environment-variable propagation to TestHostOrchestratorHost / TestHostControllersTestHost controlled children
TerminalOutputDevice UX line: "Cancelling test session… (press Ctrl+C again to force quit)"
Migrating existing token consumers from the legacy alias onto explicit DrainingToken / AbortingToken usage
Coordinating with the HotReload extension's own CancelKeyPress handler
Design B (IShutdownParticipant ack/extend protocol) — separate RFC

Open design questions

Should defaults be 30s/10s or come from HostOptions.ShutdownTimeout + a new AbortTimeout?
Should the IEnvironment injection be threaded explicitly from TestHostBuilder.CommonServices now, or stay defaulted to SystemEnvironment?
Are we happy with letting the 3rd Ctrl+C reach the runtime, or should we still Process.Kill ourselves?

Full RFC (motivation, prior-art table, rollout plan, alternatives) is available in my session notes and will be posted as a comment on #5345 once the prototype direction is acknowledged.

Refs #5345

Introduce a two-phase shutdown model for Microsoft.Testing.Platform so test sessions get a deterministic drain window before being aborted: - Extend internal ITestApplicationCancellationTokenSource with DrainingToken (graceful cancel) and AbortingToken (forceful abort), plus an Abort() entry point. The existing CancellationToken is kept as a back-compat alias for DrainingToken so current consumers keep observing graceful cancellation without changes. - Rewrite CTRLPlusCCancellationTokenSource with a Running -> Draining -> Aborting state machine: * 1st Ctrl+C enters Draining, starts a 30s grace timer that escalates to Aborting on elapse. * 2nd Ctrl+C escalates to Aborting immediately, starts a 10s abort-timeout safety net that FailFasts via IEnvironment. * 3rd Ctrl+C is no longer intercepted - the runtime terminates the process (matches docker compose / kubectl / npm UX). - Add 6 unit tests covering initial state, single/idempotent cancel, abort, grace-period escalation, and zero-grace escalation. Passes on net9.0 and net462. CLI options (--shutdown-grace-period, --shutdown-abort-timeout), env- var propagation to controlled hosts, TerminalOutputDevice UX updates, and migration of existing token consumers are intentionally deferred to follow-up PRs and tracked in the RFC. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Prototype implementation of a two-phase shutdown model for Microsoft.Testing.Platform (MTP), introducing distinct “Draining” vs “Aborting” cancellation semantics to address Ctrl+C behavior discussed in #5345 while keeping back-compat for existing token consumers.

Changes:

Extend ITestApplicationCancellationTokenSource with DrainingToken, AbortingToken, and an Abort() escalation API (with CancellationToken preserved as a Draining alias).
Rewrite CTRLPlusCCancellationTokenSource to implement a Running → Draining → Aborting phase model with Ctrl+C escalation and grace/abort timers.
Add unit tests covering the new phase/token behavior.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs	Adds two-phase shutdown tokens and `Abort()` API while preserving legacy token alias.
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs	Implements the phased shutdown state machine, Ctrl+C escalation logic, and timers.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs	Updates local test stub to satisfy the extended cancellation token source interface.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs	Adds new unit tests validating draining/aborting semantics and grace escalation.

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 5

When the test-application cancellation token is signalled and shutdown takes longer than expected, MTP now periodically prints a 'Still waiting for: ...' warning listing the extensions and consumers that have not yet returned. This makes a hanging Ctrl+C observable without users having to inspect the process state. Adds a new internal IShutdownProgressReporter service plus a default ShutdownProgressReporter implementation. The reporter wraps the three known blocking await sites: * ITestSessionLifetimeHandler.OnTestSessionFinishingAsync (both non-consumer and consumer passes in CommonTestHost) * IAsyncConsumerDataProcessor.DrainDataAsync per consumer in AsynchronousMessageBus The watchdog only starts after the cancellation token fires, waits a quiet window (3s) to avoid noise on clean shutdowns, then polls every second. Output goes through IOutputDevice as a WarningMessageOutputDeviceData. Refs #5345. Complementary to #8580 - the same trackers will feed the eventual `force-killed because X didn't drain` message once the phased-shutdown RFC lands. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Dispose() now detaches the Console.CancelKeyPress handler and disposes any pending escalation CancellationTokenSources so callbacks don't fire after the source is disposed and we don't keep the instance alive through the static console event. - OnConsoleCancelKeyPressed guards against post-Dispose invocations and routes the 2nd Ctrl+C through Abort() rather than EnterAborting() directly, keeping the Running -> Draining -> Aborting invariant. - EnterAborting() now calls EnterDraining() first so the legacy CancellationToken / DrainingToken are always signaled when AbortingToken is canceled, and uses CompareExchange(Draining -> Aborting) instead of an unconditional Exchange. - ScheduleEscalation retains the timer CancellationTokenSource so it can be disposed in Dispose(). - Test GracePeriodElapse_EscalatesToAborting is now event-driven via a TaskCompletionSource registered on AbortingToken (no more Task.Delay polling loop). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-06-05T12:14:12Z

Copilot resolve the merge conflicts in this pull request

…ased-shutdown # Conflicts: # src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs # test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>

Copilot · 2026-06-05T12:23:27Z

Copilot resolve the merge conflicts in this pull request

Done. Merged origin/main into this branch (commit 069d9ad). The two conflicts were in:

CTRLPlusCCancellationTokenSource.cs — resolved by keeping our two-phase implementation
CTRLPlusCCancellationTokenSourceTests.cs — resolved by keeping our phased-shutdown tests

Add coverage for Console.CancelKeyPress unsubscription and keep the phase field mutable while using the newer Lock type where available. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 3

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-05-25T20:52:52Z

Summary

Prototype of a two-phase graceful shutdown for Microsoft.Testing.Platform, exploring the design discussed in #5345 (see this comment).

Status: draft / RFC — opened for early design feedback. CLI options and most consumer migrations are intentionally deferred.

Motivation

Today MTP exposes a single ITestApplicationCancellationTokenSource.CancellationToken. On Ctrl+C, every consumer (tests, extensions, hosts) receives the same signal at the same time, and there is no contract distinguishing "please wind down gracefully" from "stop right now". This conflates the two shutdown modes that virtually every other host-style runtime treats as distinct phases (systemd EXTEND_TIMEOUT_USEC, macOS NSTerminateLater, AWS Lambda Extensions SHUTDOWN, Kubernetes preStop / terminationGracePeriodSeconds, docker compose 2-press SIGTERM→SIGKILL, Vitest teardownTimeout, …).

What's in this PR

A working prototype of Design A from the offline analysis:

Concept	Implementation
Two cancellation tokens	`DrainingToken` (graceful) and `AbortingToken` (forceful) on the internal `ITestApplicationCancellationTokenSource`
Back-compat	Existing `CancellationToken` is preserved as an alias of `DrainingToken` so the ~14 current consumers keep working unchanged
`Abort()` API	Explicit programmatic escalation entry point
State machine	`Running → Draining → Aborting` using `Interlocked.CompareExchange` for atomic phase transitions
Ctrl+C UX (matches docker compose / kubectl / npm)	1st press → Draining (+ 30s grace timer); 2nd press → Aborting (+ 10s abort-timeout FailFast safety net); 3rd press → not intercepted, runtime kills the process
Auto-escalation	Grace-period timer escalates Draining → Aborting if drain takes too long
Last-resort	Abort-timeout uses `IEnvironment.FailFast` (banned `Environment.FailFast` replaced with the injectable wrapper)

Files

src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs — extended interface
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs — full rewrite
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs — inline mock updated
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs — 6 new unit tests

Verification

Builds clean on net8.0 / net9.0 / netstandard2.0
6/6 new tests pass on net9.0
6/6 new tests pass on net462 (confirms no DIM/runtime issues for the MSTest.TestAdapter consumer of the netstandard2.0 build)
24/24 adjacent CommonHost / Cancellation / StopPolic* tests still pass — no regressions

Intentionally deferred (follow-ups)

To keep this PR reviewable, the following are explicitly NOT in scope and will land as separate PRs once the core direction is approved:

CLI options --shutdown-grace-period and --shutdown-abort-timeout via PlatformCommandLineProvider + HelpInfoTests acceptance assertions
Environment-variable propagation to TestHostOrchestratorHost / TestHostControllersTestHost controlled children
TerminalOutputDevice UX line: "Cancelling test session… (press Ctrl+C again to force quit)"
Migrating existing token consumers from the legacy alias onto explicit DrainingToken / AbortingToken usage
Coordinating with the HotReload extension's own CancelKeyPress handler
Design B (IShutdownParticipant ack/extend protocol) — separate RFC

Open design questions

Should defaults be 30s/10s or come from HostOptions.ShutdownTimeout + a new AbortTimeout?
Should the IEnvironment injection be threaded explicitly from TestHostBuilder.CommonServices now, or stay defaulted to SystemEnvironment?
Are we happy with letting the 3rd Ctrl+C reach the runtime, or should we still Process.Kill ourselves?

Full RFC (motivation, prior-art table, rollout plan, alternatives) is available in my session notes and will be posted as a comment on #5345 once the prototype direction is acknowledged.

Refs #5345

Introduce a two-phase shutdown model for Microsoft.Testing.Platform so test sessions get a deterministic drain window before being aborted: - Extend internal ITestApplicationCancellationTokenSource with DrainingToken (graceful cancel) and AbortingToken (forceful abort), plus an Abort() entry point. The existing CancellationToken is kept as a back-compat alias for DrainingToken so current consumers keep observing graceful cancellation without changes. - Rewrite CTRLPlusCCancellationTokenSource with a Running -> Draining -> Aborting state machine: * 1st Ctrl+C enters Draining, starts a 30s grace timer that escalates to Aborting on elapse. * 2nd Ctrl+C escalates to Aborting immediately, starts a 10s abort-timeout safety net that FailFasts via IEnvironment. * 3rd Ctrl+C is no longer intercepted - the runtime terminates the process (matches docker compose / kubectl / npm UX). - Add 6 unit tests covering initial state, single/idempotent cancel, abort, grace-period escalation, and zero-grace escalation. Passes on net9.0 and net462. CLI options (--shutdown-grace-period, --shutdown-abort-timeout), env- var propagation to controlled hosts, TerminalOutputDevice UX updates, and migration of existing token consumers are intentionally deferred to follow-up PRs and tracked in the RFC. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Prototype implementation of a two-phase shutdown model for Microsoft.Testing.Platform (MTP), introducing distinct “Draining” vs “Aborting” cancellation semantics to address Ctrl+C behavior discussed in #5345 while keeping back-compat for existing token consumers.

Changes:

Extend ITestApplicationCancellationTokenSource with DrainingToken, AbortingToken, and an Abort() escalation API (with CancellationToken preserved as a Draining alias).
Rewrite CTRLPlusCCancellationTokenSource to implement a Running → Draining → Aborting phase model with Ctrl+C escalation and grace/abort timers.
Add unit tests covering the new phase/token behavior.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs	Adds two-phase shutdown tokens and `Abort()` API while preserving legacy token alias.
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs	Implements the phased shutdown state machine, Ctrl+C escalation logic, and timers.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs	Updates local test stub to satisfy the extended cancellation token source interface.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs	Adds new unit tests validating draining/aborting semantics and grace escalation.

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 5

When the test-application cancellation token is signalled and shutdown takes longer than expected, MTP now periodically prints a 'Still waiting for: ...' warning listing the extensions and consumers that have not yet returned. This makes a hanging Ctrl+C observable without users having to inspect the process state. Adds a new internal IShutdownProgressReporter service plus a default ShutdownProgressReporter implementation. The reporter wraps the three known blocking await sites: * ITestSessionLifetimeHandler.OnTestSessionFinishingAsync (both non-consumer and consumer passes in CommonTestHost) * IAsyncConsumerDataProcessor.DrainDataAsync per consumer in AsynchronousMessageBus The watchdog only starts after the cancellation token fires, waits a quiet window (3s) to avoid noise on clean shutdowns, then polls every second. Output goes through IOutputDevice as a WarningMessageOutputDeviceData. Refs #5345. Complementary to #8580 - the same trackers will feed the eventual `force-killed because X didn't drain` message once the phased-shutdown RFC lands. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Dispose() now detaches the Console.CancelKeyPress handler and disposes any pending escalation CancellationTokenSources so callbacks don't fire after the source is disposed and we don't keep the instance alive through the static console event. - OnConsoleCancelKeyPressed guards against post-Dispose invocations and routes the 2nd Ctrl+C through Abort() rather than EnterAborting() directly, keeping the Running -> Draining -> Aborting invariant. - EnterAborting() now calls EnterDraining() first so the legacy CancellationToken / DrainingToken are always signaled when AbortingToken is canceled, and uses CompareExchange(Draining -> Aborting) instead of an unconditional Exchange. - ScheduleEscalation retains the timer CancellationTokenSource so it can be disposed in Dispose(). - Test GracePeriodElapse_EscalatesToAborting is now event-driven via a TaskCompletionSource registered on AbortingToken (no more Task.Delay polling loop). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-06-05T12:14:12Z

Copilot resolve the merge conflicts in this pull request

…ased-shutdown # Conflicts: # src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs # test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>

Copilot · 2026-06-05T12:23:27Z

Copilot resolve the merge conflicts in this pull request

Done. Merged origin/main into this branch (commit 069d9ad). The two conflicts were in:

CTRLPlusCCancellationTokenSource.cs — resolved by keeping our two-phase implementation
CTRLPlusCCancellationTokenSourceTests.cs — resolved by keeping our phased-shutdown tests

Add coverage for Console.CancelKeyPress unsubscription and keep the phase field mutable while using the newer Lock type where available. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 3

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-05-25T20:52:52Z

Summary

Prototype of a two-phase graceful shutdown for Microsoft.Testing.Platform, exploring the design discussed in #5345 (see this comment).

Status: draft / RFC — opened for early design feedback. CLI options and most consumer migrations are intentionally deferred.

Motivation

Today MTP exposes a single ITestApplicationCancellationTokenSource.CancellationToken. On Ctrl+C, every consumer (tests, extensions, hosts) receives the same signal at the same time, and there is no contract distinguishing "please wind down gracefully" from "stop right now". This conflates the two shutdown modes that virtually every other host-style runtime treats as distinct phases (systemd EXTEND_TIMEOUT_USEC, macOS NSTerminateLater, AWS Lambda Extensions SHUTDOWN, Kubernetes preStop / terminationGracePeriodSeconds, docker compose 2-press SIGTERM→SIGKILL, Vitest teardownTimeout, …).

What's in this PR

A working prototype of Design A from the offline analysis:

Concept	Implementation
Two cancellation tokens	`DrainingToken` (graceful) and `AbortingToken` (forceful) on the internal `ITestApplicationCancellationTokenSource`
Back-compat	Existing `CancellationToken` is preserved as an alias of `DrainingToken` so the ~14 current consumers keep working unchanged
`Abort()` API	Explicit programmatic escalation entry point
State machine	`Running → Draining → Aborting` using `Interlocked.CompareExchange` for atomic phase transitions
Ctrl+C UX (matches docker compose / kubectl / npm)	1st press → Draining (+ 30s grace timer); 2nd press → Aborting (+ 10s abort-timeout FailFast safety net); 3rd press → not intercepted, runtime kills the process
Auto-escalation	Grace-period timer escalates Draining → Aborting if drain takes too long
Last-resort	Abort-timeout uses `IEnvironment.FailFast` (banned `Environment.FailFast` replaced with the injectable wrapper)

Files

src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs — extended interface
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs — full rewrite
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs — inline mock updated
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs — 6 new unit tests

Verification

Builds clean on net8.0 / net9.0 / netstandard2.0
6/6 new tests pass on net9.0
6/6 new tests pass on net462 (confirms no DIM/runtime issues for the MSTest.TestAdapter consumer of the netstandard2.0 build)
24/24 adjacent CommonHost / Cancellation / StopPolic* tests still pass — no regressions

Intentionally deferred (follow-ups)

To keep this PR reviewable, the following are explicitly NOT in scope and will land as separate PRs once the core direction is approved:

CLI options --shutdown-grace-period and --shutdown-abort-timeout via PlatformCommandLineProvider + HelpInfoTests acceptance assertions
Environment-variable propagation to TestHostOrchestratorHost / TestHostControllersTestHost controlled children
TerminalOutputDevice UX line: "Cancelling test session… (press Ctrl+C again to force quit)"
Migrating existing token consumers from the legacy alias onto explicit DrainingToken / AbortingToken usage
Coordinating with the HotReload extension's own CancelKeyPress handler
Design B (IShutdownParticipant ack/extend protocol) — separate RFC

Open design questions

Should defaults be 30s/10s or come from HostOptions.ShutdownTimeout + a new AbortTimeout?
Should the IEnvironment injection be threaded explicitly from TestHostBuilder.CommonServices now, or stay defaulted to SystemEnvironment?
Are we happy with letting the 3rd Ctrl+C reach the runtime, or should we still Process.Kill ourselves?

Full RFC (motivation, prior-art table, rollout plan, alternatives) is available in my session notes and will be posted as a comment on #5345 once the prototype direction is acknowledged.

Refs #5345

Introduce a two-phase shutdown model for Microsoft.Testing.Platform so test sessions get a deterministic drain window before being aborted: - Extend internal ITestApplicationCancellationTokenSource with DrainingToken (graceful cancel) and AbortingToken (forceful abort), plus an Abort() entry point. The existing CancellationToken is kept as a back-compat alias for DrainingToken so current consumers keep observing graceful cancellation without changes. - Rewrite CTRLPlusCCancellationTokenSource with a Running -> Draining -> Aborting state machine: * 1st Ctrl+C enters Draining, starts a 30s grace timer that escalates to Aborting on elapse. * 2nd Ctrl+C escalates to Aborting immediately, starts a 10s abort-timeout safety net that FailFasts via IEnvironment. * 3rd Ctrl+C is no longer intercepted - the runtime terminates the process (matches docker compose / kubectl / npm UX). - Add 6 unit tests covering initial state, single/idempotent cancel, abort, grace-period escalation, and zero-grace escalation. Passes on net9.0 and net462. CLI options (--shutdown-grace-period, --shutdown-abort-timeout), env- var propagation to controlled hosts, TerminalOutputDevice UX updates, and migration of existing token consumers are intentionally deferred to follow-up PRs and tracked in the RFC. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Prototype implementation of a two-phase shutdown model for Microsoft.Testing.Platform (MTP), introducing distinct “Draining” vs “Aborting” cancellation semantics to address Ctrl+C behavior discussed in #5345 while keeping back-compat for existing token consumers.

Changes:

Extend ITestApplicationCancellationTokenSource with DrainingToken, AbortingToken, and an Abort() escalation API (with CancellationToken preserved as a Draining alias).
Rewrite CTRLPlusCCancellationTokenSource to implement a Running → Draining → Aborting phase model with Ctrl+C escalation and grace/abort timers.
Add unit tests covering the new phase/token behavior.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs	Adds two-phase shutdown tokens and `Abort()` API while preserving legacy token alias.
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs	Implements the phased shutdown state machine, Ctrl+C escalation logic, and timers.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs	Updates local test stub to satisfy the extended cancellation token source interface.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs	Adds new unit tests validating draining/aborting semantics and grace escalation.

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 5

When the test-application cancellation token is signalled and shutdown takes longer than expected, MTP now periodically prints a 'Still waiting for: ...' warning listing the extensions and consumers that have not yet returned. This makes a hanging Ctrl+C observable without users having to inspect the process state. Adds a new internal IShutdownProgressReporter service plus a default ShutdownProgressReporter implementation. The reporter wraps the three known blocking await sites: * ITestSessionLifetimeHandler.OnTestSessionFinishingAsync (both non-consumer and consumer passes in CommonTestHost) * IAsyncConsumerDataProcessor.DrainDataAsync per consumer in AsynchronousMessageBus The watchdog only starts after the cancellation token fires, waits a quiet window (3s) to avoid noise on clean shutdowns, then polls every second. Output goes through IOutputDevice as a WarningMessageOutputDeviceData. Refs #5345. Complementary to #8580 - the same trackers will feed the eventual `force-killed because X didn't drain` message once the phased-shutdown RFC lands. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Dispose() now detaches the Console.CancelKeyPress handler and disposes any pending escalation CancellationTokenSources so callbacks don't fire after the source is disposed and we don't keep the instance alive through the static console event. - OnConsoleCancelKeyPressed guards against post-Dispose invocations and routes the 2nd Ctrl+C through Abort() rather than EnterAborting() directly, keeping the Running -> Draining -> Aborting invariant. - EnterAborting() now calls EnterDraining() first so the legacy CancellationToken / DrainingToken are always signaled when AbortingToken is canceled, and uses CompareExchange(Draining -> Aborting) instead of an unconditional Exchange. - ScheduleEscalation retains the timer CancellationTokenSource so it can be disposed in Dispose(). - Test GracePeriodElapse_EscalatesToAborting is now event-driven via a TaskCompletionSource registered on AbortingToken (no more Task.Delay polling loop). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-06-05T12:14:12Z

Copilot resolve the merge conflicts in this pull request

…ased-shutdown # Conflicts: # src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs # test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>

Copilot · 2026-06-05T12:23:27Z

Copilot resolve the merge conflicts in this pull request

Done. Merged origin/main into this branch (commit 069d9ad). The two conflicts were in:

CTRLPlusCCancellationTokenSource.cs — resolved by keeping our two-phase implementation
CTRLPlusCCancellationTokenSourceTests.cs — resolved by keeping our phased-shutdown tests

Add coverage for Console.CancelKeyPress unsubscription and keep the phase field mutable while using the newer Lock type where available. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 3

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-05-25T20:52:52Z

Summary

Prototype of a two-phase graceful shutdown for Microsoft.Testing.Platform, exploring the design discussed in #5345 (see this comment).

Status: draft / RFC — opened for early design feedback. CLI options and most consumer migrations are intentionally deferred.

Motivation

Today MTP exposes a single ITestApplicationCancellationTokenSource.CancellationToken. On Ctrl+C, every consumer (tests, extensions, hosts) receives the same signal at the same time, and there is no contract distinguishing "please wind down gracefully" from "stop right now". This conflates the two shutdown modes that virtually every other host-style runtime treats as distinct phases (systemd EXTEND_TIMEOUT_USEC, macOS NSTerminateLater, AWS Lambda Extensions SHUTDOWN, Kubernetes preStop / terminationGracePeriodSeconds, docker compose 2-press SIGTERM→SIGKILL, Vitest teardownTimeout, …).

What's in this PR

A working prototype of Design A from the offline analysis:

Concept	Implementation
Two cancellation tokens	`DrainingToken` (graceful) and `AbortingToken` (forceful) on the internal `ITestApplicationCancellationTokenSource`
Back-compat	Existing `CancellationToken` is preserved as an alias of `DrainingToken` so the ~14 current consumers keep working unchanged
`Abort()` API	Explicit programmatic escalation entry point
State machine	`Running → Draining → Aborting` using `Interlocked.CompareExchange` for atomic phase transitions
Ctrl+C UX (matches docker compose / kubectl / npm)	1st press → Draining (+ 30s grace timer); 2nd press → Aborting (+ 10s abort-timeout FailFast safety net); 3rd press → not intercepted, runtime kills the process
Auto-escalation	Grace-period timer escalates Draining → Aborting if drain takes too long
Last-resort	Abort-timeout uses `IEnvironment.FailFast` (banned `Environment.FailFast` replaced with the injectable wrapper)

Files

src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs — extended interface
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs — full rewrite
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs — inline mock updated
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs — 6 new unit tests

Verification

Builds clean on net8.0 / net9.0 / netstandard2.0
6/6 new tests pass on net9.0
6/6 new tests pass on net462 (confirms no DIM/runtime issues for the MSTest.TestAdapter consumer of the netstandard2.0 build)
24/24 adjacent CommonHost / Cancellation / StopPolic* tests still pass — no regressions

Intentionally deferred (follow-ups)

To keep this PR reviewable, the following are explicitly NOT in scope and will land as separate PRs once the core direction is approved:

CLI options --shutdown-grace-period and --shutdown-abort-timeout via PlatformCommandLineProvider + HelpInfoTests acceptance assertions
Environment-variable propagation to TestHostOrchestratorHost / TestHostControllersTestHost controlled children
TerminalOutputDevice UX line: "Cancelling test session… (press Ctrl+C again to force quit)"
Migrating existing token consumers from the legacy alias onto explicit DrainingToken / AbortingToken usage
Coordinating with the HotReload extension's own CancelKeyPress handler
Design B (IShutdownParticipant ack/extend protocol) — separate RFC

Open design questions

Should defaults be 30s/10s or come from HostOptions.ShutdownTimeout + a new AbortTimeout?
Should the IEnvironment injection be threaded explicitly from TestHostBuilder.CommonServices now, or stay defaulted to SystemEnvironment?
Are we happy with letting the 3rd Ctrl+C reach the runtime, or should we still Process.Kill ourselves?

Full RFC (motivation, prior-art table, rollout plan, alternatives) is available in my session notes and will be posted as a comment on #5345 once the prototype direction is acknowledged.

Refs #5345

Introduce a two-phase shutdown model for Microsoft.Testing.Platform so test sessions get a deterministic drain window before being aborted: - Extend internal ITestApplicationCancellationTokenSource with DrainingToken (graceful cancel) and AbortingToken (forceful abort), plus an Abort() entry point. The existing CancellationToken is kept as a back-compat alias for DrainingToken so current consumers keep observing graceful cancellation without changes. - Rewrite CTRLPlusCCancellationTokenSource with a Running -> Draining -> Aborting state machine: * 1st Ctrl+C enters Draining, starts a 30s grace timer that escalates to Aborting on elapse. * 2nd Ctrl+C escalates to Aborting immediately, starts a 10s abort-timeout safety net that FailFasts via IEnvironment. * 3rd Ctrl+C is no longer intercepted - the runtime terminates the process (matches docker compose / kubectl / npm UX). - Add 6 unit tests covering initial state, single/idempotent cancel, abort, grace-period escalation, and zero-grace escalation. Passes on net9.0 and net462. CLI options (--shutdown-grace-period, --shutdown-abort-timeout), env- var propagation to controlled hosts, TerminalOutputDevice UX updates, and migration of existing token consumers are intentionally deferred to follow-up PRs and tracked in the RFC. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Prototype implementation of a two-phase shutdown model for Microsoft.Testing.Platform (MTP), introducing distinct “Draining” vs “Aborting” cancellation semantics to address Ctrl+C behavior discussed in #5345 while keeping back-compat for existing token consumers.

Changes:

Extend ITestApplicationCancellationTokenSource with DrainingToken, AbortingToken, and an Abort() escalation API (with CancellationToken preserved as a Draining alias).
Rewrite CTRLPlusCCancellationTokenSource to implement a Running → Draining → Aborting phase model with Ctrl+C escalation and grace/abort timers.
Add unit tests covering the new phase/token behavior.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/Services/ITestApplicationCancellationTokenSource.cs	Adds two-phase shutdown tokens and `Abort()` API while preserving legacy token alias.
src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs	Implements the phased shutdown state machine, Ctrl+C escalation logic, and timers.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Hosts/CommonHostTests.cs	Updates local test stub to satisfy the extended cancellation token source interface.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs	Adds new unit tests validating draining/aborting semantics and grace escalation.

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 5

When the test-application cancellation token is signalled and shutdown takes longer than expected, MTP now periodically prints a 'Still waiting for: ...' warning listing the extensions and consumers that have not yet returned. This makes a hanging Ctrl+C observable without users having to inspect the process state. Adds a new internal IShutdownProgressReporter service plus a default ShutdownProgressReporter implementation. The reporter wraps the three known blocking await sites: * ITestSessionLifetimeHandler.OnTestSessionFinishingAsync (both non-consumer and consumer passes in CommonTestHost) * IAsyncConsumerDataProcessor.DrainDataAsync per consumer in AsynchronousMessageBus The watchdog only starts after the cancellation token fires, waits a quiet window (3s) to avoid noise on clean shutdowns, then polls every second. Output goes through IOutputDevice as a WarningMessageOutputDeviceData. Refs #5345. Complementary to #8580 - the same trackers will feed the eventual `force-killed because X didn't drain` message once the phased-shutdown RFC lands. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Dispose() now detaches the Console.CancelKeyPress handler and disposes any pending escalation CancellationTokenSources so callbacks don't fire after the source is disposed and we don't keep the instance alive through the static console event. - OnConsoleCancelKeyPressed guards against post-Dispose invocations and routes the 2nd Ctrl+C through Abort() rather than EnterAborting() directly, keeping the Running -> Draining -> Aborting invariant. - EnterAborting() now calls EnterDraining() first so the legacy CancellationToken / DrainingToken are always signaled when AbortingToken is canceled, and uses CompareExchange(Draining -> Aborting) instead of an unconditional Exchange. - ScheduleEscalation retains the timer CancellationTokenSource so it can be disposed in Dispose(). - Test GracePeriodElapse_EscalatesToAborting is now event-driven via a TaskCompletionSource registered on AbortingToken (no more Task.Delay polling loop). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Amaury Levé (Evangelink) · 2026-06-05T12:14:12Z

Copilot resolve the merge conflicts in this pull request

…ased-shutdown # Conflicts: # src/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs # test/UnitTests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>

Copilot · 2026-06-05T12:23:27Z

Copilot resolve the merge conflicts in this pull request

Done. Merged origin/main into this branch (commit 069d9ad). The two conflicts were in:

CTRLPlusCCancellationTokenSource.cs — resolved by keeping our two-phase implementation
CTRLPlusCCancellationTokenSourceTests.cs — resolved by keeping our phased-shutdown tests

Add coverage for Console.CancelKeyPress unsubscription and keep the phase field mutable while using the newer Lock type where available. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 4/4 changed files
Comments generated: 3

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

CopilotAI review requested due to automatic review settings May 25, 2026 20:52

Copilotstarted reviewing on behalf of Amaury Levé (Evangelink)May 25, 2026 20:53 View session

Amaury Levé (Evangelink) mentioned this pull request May 25, 2026
CTRL+C does not complete the test run when there is long running test #5345
Closed

CopilotAI reviewed May 25, 2026
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github-code-qualityBot found potential problems May 25, 2026
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Comment threadsrc/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs Fixed

Amaury Levé (Evangelink) mentioned this pull request May 25, 2026
Surface still-running extensions during MTP shutdown (refs #5345) #8582
Merged

github-code-qualityBot found potential problems Jun 4, 2026
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Comment threadsrc/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs Fixed

This was referenced Jun 5, 2026
Ignore auto-generated AGENTS.md in markdownlint #8851
Merged
Also ignore copilot-curate.instructions.md from markdownlint #8852
Merged

Copilotstarted work on behalf of Amaury Levé (Evangelink)June 5, 2026 12:14 View session

CopilotAI review requested due to automatic review settings June 5, 2026 12:23

Amaury Levé (Evangelink) removed the request for review from Copilot June 5, 2026 12:23

Copilotfinished work on behalf of Amaury Levé (Evangelink)June 5, 2026 12:23

Address phased shutdown review feedback
ea75551
Add coverage for Console.CancelKeyPress unsubscription and keep the phase field mutable while using the newer Lock type where available. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

CopilotAI review requested due to automatic review settings June 7, 2026 08:00

Copilotstarted reviewing on behalf of Amaury Levé (Evangelink)June 7, 2026 08:00 View session

CopilotAI reviewed Jun 7, 2026
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Comment thread...Tests/Microsoft.Testing.Platform.UnitTests/Services/CTRLPlusCCancellationTokenSourceTests.cs Fixed
Comment threadsrc/Platform/Microsoft.Testing.Platform/Services/CTRLPlusCCancellationTokenSource.cs Fixed

Address phased shutdown lifecycle feedback
44052b6
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>