#110062
Profiler users invokingEnumThreads within aRuntimeSuspendFinished callback will cause aninfinite wait because theEnumThreads will recursively acquire/release the ThreadStore lock.

Regression

This did not occur in .NET 8.0. The recursive ThreadStoreLock acquire/release was always there, butthe condition that previously prevented this case causing an infinite wait was removed in#101782

Testing

The issue was reproduced locally and the fix was confirmed locally.
The issue was missed previously because there were no profiler tests covering this edge-case scenario. It is hard to cover all the ways our customers will use Profiler APIs.
A runtime test was added for this particular scenario, invoking theEnumThreads API within aRuntimeSuspendFinished callback.

Risk

Low. The changes only affect Profiler users that specifically invokeEnumThreads within aRuntimeSuspendFinished callback and trigger a GC.

IMPORTANT: If this backport is for a servicing release, please verify that:

The PR target branch isrelease/X.0-staging, notrelease/X.0.

Package authoring no longer needed in .NET 9

IMPORTANT: Starting with .NET 9, you no longer need to edit a NuGet package's csproj to enable building and bump the version.
Keep in mind that we still need package authoring in .NET 8 and older versions.

mdh1418 added4 commits

December 12, 2024 19:54

[Profiler] Avoid Recursive ThreadStoreLock

526a803

Profiling Enumerators look to acquire the ThreadStoreLock.In release config, re-acquiring the ThreadStoreLock andreleasing it in ProfilerThreadEnum::Init will causeproblems if the callback invoking EnumThread has logicthat depends on the ThreadStoreLock being held.To avoid recursively acquiring the ThreadStoreLock,expand the condition when the profiling thread enumeratorshouldn't acquire the ThreadStoreLock.

[Profiler] Change order to set fProfilerRequestedRuntimeSuspend

bc59f5c

There was a potential race condition when setting the flagbefore suspending and resetting the flag after restarting.For example, if the thread restarting runtime is preemptedright after resuming runtime, the flag could remain unsetby the time another thread looks to suspend runtime, whichwould see that the flag as set.

[Profiler][Tests] Add unit test for EnumThreads during suspension

2c4aba9

[Profiler][Tests] Fixup EnumThreads test

4f6f046