[release/8.0] Fix a possible infinite wait for GC completion at process shutdown. #107844
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…own on Windows (dotnet#103877)" Fixes:107800 * Use RtlDllShutdownInProgress to detect process shutdown on Windows Switching to cooperative mode is not safe during process shutdown on Windows. Process shutdown can terminate a thread in the middle of the GC. The shutdown thread deadlocks if it tries to switch to cooperative mode and wait for the GC to finish in this situation. Use RtlDllShutdownInProgress Windows API to detect process shutdown to avoid waiting for GC completion when that may lead to deadlocks.
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mangod9
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Co-authored-by: Manish Godse <61718172+mangod9@users.noreply.github.com>
jeffschwMSFT
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Sep 19, 2024
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Fixes: #107800
This is a partial/minimal port of #103877.
Cooperative process cleanup is fragile and #103877 addresses many potential issues, however the change is not small and in parts works on top of 9.0 changes.
This is a port of a small part of the change to address a specific scenario that is known to affect end users.
Customer Impact
Bug was reported by internal partners. In some relatively infrequent cases a worker process may get stuck at exiting.
Such "stuck" processes could become a nuisance, especially when the memory footprint of workers is very large.
Regression
Appears to be introduced in .NET 6 as the repro scenario passes with 5.0, but deadlocks in 6.0, 8.0 and early 9.0 previews
Testing
Added a targeted unit test.
Risk
Small.
The code already tries to detect if the process is shutting down. We just use a more reliable mechanism - a new Windows API introduced in Win10 (
RtlDllShutdownInProgress)The main concern is that there could be other similar issues.
The 9.0 fix addresses several more patterns similar to the one involved here. They may or may not result in actual failures and there is some added risk that proactive fixing of other areas may actually break something, which we decided not to do in a servicing fix.