fix(profiling): release the EventPipe session when the SDK shuts down

[jamescrosswell]

SamplingTransactionProfilerFactory.Dispose() disposed the antecedent Task<SampleProfilerSession> rather than the session it wraps, so the EventPipeSession was never stopped.

Tracing it through, that line is the last of three defects sitting between "SDK shuts down" and "EventPipe session released" — fixing it alone would not have changed anything observable:

1. SampleProfilerSession.Stop() skipped its own disposals on the happy path. _processing was built with TaskContinuationOptions.OnlyOnFaulted; when eventSource.Process() returns normally the continuation criteria aren't met, so the continuation transitions to Canceled and _processing.Wait() throws AggregateException(TaskCanceledException). EventPipeSession.Dispose() and TraceLogEventSource.Dispose() sat after that call and were never reached — the catch logged Error during sampler profiler session shutdown. and swallowed it. The continuation is now unconditional, and the disposals moved into a finally with a bounded drain wait so shutdown can't hang.

2. Nothing ever called Dispose() on the factory. ProfilingIntegration was not IDisposable, so Hub never added it to _integrationsToCleanup, and the factory's only other reference is options.TransactionProfilerFactory, which nothing disposes. The integration is now IDisposable and disposes the factory — but only one it created itself, since TransactionProfilerFactory may have been supplied elsewhere.

3. The reported bug. Dispose() now waits (bounded) for an in-flight startup and then disposes the session. It also cancels the WaitForFirstEventAsync wait, which could otherwise block indefinitely, and observes the startup task's exception if it failed.

Impact

Low, and narrower than the issue suggests. The session is created once and lives for the SDK's lifetime — SamplingTransactionProfiler.Stop() only clears _inProgress, it never touches the session — so the only disposal point is SDK shutdown, which is normally process shutdown, where the OS reclaims the handle and the TraceLog regardless. Nothing accumulates while an application runs.

Where it does bite is when the process outlives the SDK: repeated Init/Close cycles strand one EventPipeSession plus its TraceLog per cycle, and hosts that close Sentry but keep running never release the pipe.

The issue links this to the Windows Service memory growth in #3375. That link doesn't hold up — a service that initialises Sentry once would never reach any of these paths.

Notes

• Defect 1 has a visible signature in diagnostic logs: Error during sampler profiler session shutdown. on every clean shutdown with profiling enabled. Worth asking anyone reporting profiler-related growth whether they see it.
• Hub.Dispose() now does real work for profiling users where it previously did none. Both new waits are bounded at 2s so a wedged EventPipe session can't hang shutdown.
• The existing Sentry.Profiling tests are largely Skip.If(TestEnvironment.IsGitHubActions), so the two ProfilingIntegration tests are plain [Fact]s that do run in CI; only the session-level test follows the existing skip pattern.

Fixes #5418

[codecov]

Codecov Report

❌ Patch coverage is 65.78947% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.74%. Comparing base (e669940) to head (948f8b5).

Files with missing lines	Patch %	Lines
src/Sentry.Profiling/SampleProfilerSession.cs	33.33%	6 Missing and 2 partials ⚠️
...ry.Profiling/SamplingTransactionProfilerFactory.cs	73.68%	4 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5470      +/-   ##
==========================================
+ Coverage   74.71%   74.74%   +0.03%     
==========================================
  Files         513      513              
  Lines       18729    18758      +29     
  Branches     3663     3669       +6     
==========================================
+ Hits        13993    14021      +28     
+ Misses       3865     3858       -7     
- Partials      871      879       +8     

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