Fix System.Text.Json IAsyncEnumerator disposal on cancellation

[eiriktsarpalis]

Addresses an issue in System.Text.Json IAsyncEnumerable serialization where, in the event of a user-thrown exception, the serializer will attempt to dispose the IAsyncEnumerator instance without making sure that there are no pending MoveNextAsync() operations. In the case of compiler-generated IAsyncEnumerables, this can result in a NotSupportedException being thrown, see #51176. This issue will most typically manifest in cases where the ambient cancellation token has fired, but authors of the serialized IAsyncEnumerable are not passing that cancellation token to nested async operations.

This PR changes the IAsyncEnumerable implementation to wait on any pending MoveNextAsync() operations even if an exception has been thrown. This should not have any impact on latency provided that users take care to pass the IAsyncEnumerator cancellation token to any underlying dependencies. It also fixes an unrelated issue where in certain exceptional conditions the serializer would try to dispose the IAsyncEnumerator twice.

Fix#57360.

cc @davidfowl

[ghost]

Tagging subscribers to this area: @eiriktsarpalis, @layomia
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Addresses an issue in System.Text.Json IAsyncEnumerable serialization where, in the event of a user-thrown exception, the serializer will attempt to dispose the IAsyncEnumerator instance without making sure that there are no pending MoveNextAsync() operations. In the case of compiler-generated IAsyncEnumerables, this can result in a NotSupportedException being thrown, see #51176. This issue will most typically manifest in cases where the ambient cancellation token has fired, but authors of the serialized IAsyncEnumerable are not passing that cancellation token to nested async operations.

This PR changes the IAsyncEnumerable implementation to wait on any pending MoveNextAsync() operations even if an exception has been thrown. This should not have any impact on latency provided that users take care to pass the IAsyncEnumerator cancellation token to any underlying dependencies. It also fixes an unrelated issue where in certain exceptional conditions the serializer would try to dispose the IAsyncEnumerator twice.

Fix #57360.

cc @davidfowl

Author:	eiriktsarpalis
Assignees:	-
Labels:	area-System.Text.Json
Milestone:	-

[eiriktsarpalis]

/azp run runtime-libraries outerloop

[azure-pipelines]

No pipelines are associated with this pull request.

[eiriktsarpalis]

/azp list

[azure-pipelines]

CI/CD Pipelines for this repository:

• coreclr-gc-longrunning
• coreclr-gc-simulator
• runtime-coreclr outerloop
• runtime-coreclr jitstress
• runtime-coreclr jitstressregs
• runtime-coreclr jitstress2-jitstressregs
• runtime-coreclr gcstress0x3-gcstress0xc
• runtime-coreclr gcstress-extra
• runtime-coreclr r2r-extra
• runtime-coreclr jitstress-isas-x86
• runtime-coreclr jitstress-isas-arm
• runtime-coreclr jitstressregs-x86
• runtime-coreclr libraries-jitstressregs
• runtime-coreclr libraries-jitstress2-jitstressregs
• runtime-coreclr r2r
• runtime-coreclr runincontext
• runtime-coreclr crossgen2
• runtime-libraries-coreclr outerloop
• runtime-libraries-coreclr outerloop-windows
• runtime-libraries-coreclr outerloop-linux
• runtime-libraries-coreclr outerloop-osx
• runtime
• runtime-libraries enterprise-linux
• runtime-libraries stress-http
• runtime-libraries stress-ssl
• runtime-dev-innerloop
• runtime-coreclr crossgen2 outerloop
• coreclr-release-outerloop-nightly
• sync-runtime-to-mono
• runtime-coreclr crossgen2-composite
• runtime-jit-experimental
• runtime-coreclr libraries-jitstress
• dotnet-linker-tests
• runtime-coreclr ilasm
• runtime-coreclr crossgen2-composite gcstress
• runtime-libraries-mono outerloop
• runtime-staging
• runtime-coreclr pgo
• runtime-coreclr libraries-pgo
• coreclr-gc-regions

[eiriktsarpalis]

/azp run runtime-libraries-coreclr outerloop

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[eiriktsarpalis]

Failing tests are outerloop networking tests and a few that are already occurring in main, possibly related to the changes in #57453 and #55926.