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[tests] Re-enable concurrent e2e suite - #2083
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VaguelySerious wants to merge 6 commits into
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Flips packages/core/e2e/e2e.test.ts back to describe.concurrent. The
suite was made sequential ("temporarily disabling concurrent tests to
avoid flakiness") and never re-enabled. Each workbench now runs ~87
tests serially against its preview deploy, dominating CI wall-clock.
Putting this up as a draft to see which (if any) tests are still
flake-prone under concurrency, after recent fixes to the abort-fetch
class of flakes.Contributor
🦋 Changeset detectedLatest commit: c7060b1 The changes in this PR will be included in the next version bump. This PR includes changesets to release 18 packages
Not sure what this means? Click here to learn what changesets are. Click here if you're a maintainer who wants to add another changeset to this PR |
Contributor
📊 Benchmark Results
workflow with no steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Next.js (Turbopack) | Nitro workflow with 1 step💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) workflow with 10 sequential steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) workflow with 25 sequential steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) workflow with 50 sequential steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) Promise.all with 10 concurrent steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) Promise.all with 25 concurrent steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Next.js (Turbopack) | Nitro Promise.all with 50 concurrent steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) Promise.race with 10 concurrent steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Next.js (Turbopack) | Nitro Promise.race with 25 concurrent steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) Promise.race with 50 concurrent steps💻 Local Development
▲ Production (Vercel)
🔍 Observability: Next.js (Turbopack) | Nitro workflow with 10 sequential data payload steps (10KB)💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) workflow with 25 sequential data payload steps (10KB)💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) workflow with 50 sequential data payload steps (10KB)💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) workflow with 10 concurrent data payload steps (10KB)💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) workflow with 25 concurrent data payload steps (10KB)💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) workflow with 50 concurrent data payload steps (10KB)💻 Local Development
▲ Production (Vercel)
🔍 Observability: Next.js (Turbopack) | Nitro Stream Benchmarks(includes TTFB metrics)workflow with stream💻 Local Development
▲ Production (Vercel)
🔍 Observability: Next.js (Turbopack) | Nitro stream pipeline with 5 transform steps (1MB)💻 Local Development
▲ Production (Vercel)
🔍 Observability: Next.js (Turbopack) | Nitro 10 parallel streams (1MB each)💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) fan-out fan-in 10 streams (1MB each)💻 Local Development
▲ Production (Vercel)
🔍 Observability: Nitro | Next.js (Turbopack) SummaryFastest Framework by WorldWinner determined by most benchmark wins
Fastest World by FrameworkWinner determined by most benchmark wins
Column Definitions
Worlds:
❌ Some benchmark jobs failed:
Check the workflow run for details. |
Contributor
🧪 E2E Test Results❌ Some tests failed Summary
❌ Failed Tests▲ Vercel Production (3 failed)nitro (1 failed):
nuxt (1 failed):
sveltekit (1 failed):
💻 Local Development (5 failed)astro-stable (2 failed):
nextjs-webpack-stable-lazy-discovery-disabled (1 failed):
nuxt-stable (1 failed):
sveltekit-stable (1 failed):
📦 Local Production (1 failed)nuxt-stable (1 failed):
🐘 Local Postgres (1 failed)nuxt-stable (1 failed):
📋 Other (1 failed)e2e-local-dev-tanstack-start- (1 failed):
Details by Category❌ ▲ Vercel Production
❌ 💻 Local Development
❌ 📦 Local Production
❌ 🐘 Local Postgres
✅ 🪟 Windows
❌ 📋 Other
❌ Some E2E test jobs failed:
Check the workflow run for details. |
VaguelySerious
commented
May 22, 2026
MemberAuthor
CI verdictSpeedup is real. Per-workbench wall-clock dropped roughly 3×: from ~14–17 min on main to ~5–6 min here. Vitest's own run is even more dramatic — express went from ~15 min to 203s (~4–5× on the actual test phase). But correctness regressed. 25 checks failed: every `E2E Vercel Prod Tests (*)` matrix entry except `nitro`, plus several `E2E Local Dev/Prod/Postgres` jobs and `E2E Windows Tests`. Failure patternEvery failure I sampled is the same shape: `Error: Test timed out in 60000ms`. The which tests fail varies per workbench — i.e. it's not a single broken test:
The cluster is real though: AbortController + error-handling tests, which all do multiple sequential workflow round-trips and historically run close to the 60s budget. DiagnosisDefault vitest `maxConcurrency` is 5. With five workflow runs hammering one workbench in parallel, the heavier multi-round-trip tests appear to queue past the per-test 60s budget. Local-Postgres/Prod/Dev also fail, so it's not Vercel-specific — workflow-server (local) and the in-process world also slow under contention. Proposed next steps (separate PRs)Holding off on bundling point (5) (shortening `sleep()` durations) into this PR — the suite isn't healthy enough to add another variable. Three angles, in order of cheapest:
Leaving this PR as draft for now. Happy to iterate as a follow-up. |
The e2e suite tracked failed-run diagnostics via two module-level mutables (`trackedRuns` and `currentTestName`) that every beforeEach reset. Under describe.concurrent that races: when a test times out, the displayed diagnostic typically belongs to whichever sibling task most recently called setupRunTracking(). That's why PR #2083's first CI run showed an unrelated `errorStepCrossFile` run as the "diagnostic" for the FatalError catchability test that actually timed out — leaving us blind to the real failure cause. Switch to a `Map<taskId, PerTaskState>` keyed off `getCurrentTest().id`, with the entry dropped via onTestFinished to keep the map bounded. Also unconditionally log `[trackRun] <test> → <runId>` so we can still correlate runs from stdout even when diagnostics fetching itself stalls past the test's deadline.
…Error type in readJSON
The previous writeExclusive used `fs.writeFile(path, data, { flag: 'wx' })`,
which is atomic for the file *creation* (O_CREAT|O_EXCL) but NOT for the
subsequent data write. A concurrent reader could catch the file with
zero bytes (or just `{`) before the writer's content reached the page
cache.
This race had been silently papered over by `readHookTokenClaim`, which
swallows any SyntaxError as "no claim exists" — which is wrong: a partial
write means a claim *does* exist, just not yet flushed, and treating it as
absent lets duplicate hook tokens through. PR #2083's concurrent e2e run
also surfaced the same race on runs/<id>.json creation, producing
size=0 byte run files in CI logs.
Fix: write content to a temp file first, then `link(2)` it atomically
into place. POSIX link is atomic and fails with EEXIST if the target
already exists, preserving the exclusive-claim semantics. Readers now
either see ENOENT or the fully-populated inode — never a half-written
file.
Also preserve the SyntaxError type when annotating readJSON failures
with file path / size / content snippet, so callers like
readHookTokenClaim that intentionally swallow `error instanceof SyntaxError`
continue to work (the previous diagnostic threw a plain Error and broke
them).Vitest's default `maxConcurrency` of 5 saturates the workbench preview deploys and the in-process world runtime under `describe.concurrent`, pushing load-heavy tests (fibonacci tree spawn, multi-step abort sequencing, AbortSignal.any composition) into their per-test deadlines on PR #2083's run 4 even though the same tests pass cleanly when run sequentially. Drop to 3 in the root vitest config (only `test:e2e` and `bench` consume it — per-package configs are untouched). The Vercel-deploy matrix went from ~14-17min sequential → ~5-6min at concurrency 5; trading some of that headroom for stability is the right call now that the isolation/correctness fixes have landed.
Dropping vitest's default concurrency cap from 5 to 3 (commit c7060b1) didn't reduce the remaining e2e flake count — runs 3/4 at default concurrency=5 and run 5 at concurrency=3 all landed on exactly 15 failures. The remaining failures are external-network and source-map class issues (httpbin/postman-echo abort tests, nuxt/nextjs-webpack sourcemap assertions, fibonacci tree spawn timeouts) that lower test parallelism doesn't address. Keeping the speedup is more valuable than the small load reduction.
VaguelySerious
commented
May 22, 2026
MemberAuthor
UpdateThree substantive fixes layered on, then one revert. Final state of the PR: What was fixed
What was tried and reverted
What's left (out of scope for this PR)
VerdictThe actual concurrency-introduced isolation/correctness bugs are fixed. Concurrency speedup holds (~3× job wall-clock; ~4–5× pure vitest run). The remaining failures are pre-existing issues that the concurrency change has made more visible but doesn't itself cause. Happy to keep this draft until those classes are tackled, or to merge with a green CI rerun depending on appetite. |
This was referenced Aug 18, 2026
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Summary
describe.concurrentinpackages/core/e2e/e2e.test.ts, which was made sequential in 78048e0 ("no concurrency") with a TODO to re-enable.Test plan
E2E Vercel Prod) pass.sequentialrather than reverting the whole flipNotes
If concurrency exposes real isolation bugs (shared identifiers, cross-test state), I'll fix those before unwinding the draft state. If it's only known-flaky externals, those should already have been addressed in #2081 / follow-ups.
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