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Fix debugger app hangs related to thread exit #114887

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merged 1 commit into from
Apr 22, 2025
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Fix debugger app hangs related to thread exit #114887

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6 changes: 6 additions & 0 deletions src/coreclr/vm/threads.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2896,6 +2896,12 @@ void Thread::OnThreadTerminate(BOOL holdingLock)

}

if (m_State & TS_DebugWillSync)
{
ResetThreadState(TS_DebugWillSync);
InterlockedDecrement(&m_DebugWillSyncCount);
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Copilot AI Apr 22, 2025

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Consider adding an assertion or check to ensure that m_DebugWillSyncCount is positive before decrementing to avoid potential underflow if multiple thread terminations occur in succession.

Suggested change
InterlockedDecrement(&m_DebugWillSyncCount);
if (m_DebugWillSyncCount > 0)
{
InterlockedDecrement(&m_DebugWillSyncCount);
}

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Is this is a regression in 9, seems like it is from the bug?

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Is this is a regression in 9, seems like it is from the bug?

We believe that the issue has always existed, but something in .NET 9 may have caused it to happen more often. Perhaps it is a timing issue.

}

SetThreadState(TS_Dead);
ThreadStore::s_pThreadStore->m_DeadThreadCount++;
ThreadStore::s_pThreadStore->IncrementDeadThreadCountForGCTrigger();
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