Avoid clearing thread local handles for already unloaded LoaderAllocator - #102797

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jkotas merged 1 commit into
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Unity-Technologies:upstream-fix-threadstatic-cleanup
May 29, 2024
Merged

Avoid clearing thread local handles for already unloaded LoaderAllocator#102797
jkotas merged 1 commit into
dotnet:mainfrom
Unity-Technologies:upstream-fix-threadstatic-cleanup

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@alexey-zakharovalexey-zakharov commented May 29, 2024

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Motivation:

Fix crash in ThreadLocalBlock::FreeTLM code on thread exit which happens during Assembly unloading when Assembly contains a class with a ThreadStatic variable.

This is a new iteration of #99998 which caused issues on CI.

Details:

There seem to be a race condition between LoaderAllocator cleanup during garbage collection and thread locals cleanup on thread exit. Racing stacks are the following:

ALC/LoaderAllocator cleanup

 coreclr.dll!EEToProfInterfaceImpl::ModuleUnloadStarted(unsigned __int64 moduleId) Line 3735	C++	Symbols loaded.
coreclr.dll!ProfControlBlock::DoProfilerCallbackHelper<int (__cdecl*)(ProfilerInfo *),long (__cdecl*)(EEToProfInterfaceImpl *,unsigned __int64),unsigned __int64>(ProfilerInfo * pProfilerInfo, int(*)(ProfilerInfo *) condition, HRESULT(*)(EEToProfInterfaceImpl *, unsigned __int64) callback, HRESULT * pHR, unsigned __int64 <args_0>) Line 284	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoOneProfilerIteration(ProfilerInfo *) Line 199	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::IterateProfilers(ProfilerCallbackType) Line 207	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoProfilerCallback(ProfilerCallbackType) Line 295	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::ModuleUnloadStarted(unsigned __int64) Line 691	C++	Symbols loaded.
coreclr.dll!Module::Destruct() Line 662	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ClassLoader::FreeModules() Line 1884	C++	Symbols loaded.
coreclr.dll!ClassLoader::~ClassLoader() Line 1946	C++	Symbols loaded.
coreclr.dll!Assembly::Terminate(int) Line 311	C++	Symbols loaded.
coreclr.dll!Assembly::~Assembly() Line 244	C++	Symbols loaded.
coreclr.dll!Assembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
coreclr.dll!DomainAssembly::~DomainAssembly() Line 91	C++	Symbols loaded.
coreclr.dll!DomainAssembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
>	coreclr.dll!LoaderAllocator::GCLoaderAllocators(LoaderAllocator * pOriginalLoaderAllocator) Line 570	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 702	C++	Symbols loaded.
coreclr.dll!LoaderAllocator_Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 718	C++	Symbols loaded.
System.Private.CoreLib.dll!00007ffa9c4308f9()	Unknown	No symbols loaded.
coreclr.dll!FastCallFinalizeWorker() Line 26	Unknown	Symbols loaded.
coreclr.dll!MethodTable::CallFinalizer(Object * obj) Line 4908	C++	Symbols loaded.
[Inline Frame] coreclr.dll!CallFinalizer(Object *) Line 75	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizeAllObjects() Line 110	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadWorker(void * args) Line 354	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_DispatchInner(ManagedThreadCallState *) Line 7222	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchMiddle(ManagedThreadCallState * pCallState) Line 7266	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchOuter(ManagedThreadCallState * pCallState) Line 7425	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_NoADTransition(void(*)(void *)) Line 7494	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase::FinalizerBase(void(*)(void *)) Line 7513	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadStart(void * args) Line 403	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

Thread exit with threadlocal cleanup

>	coreclr.dll!LoaderAllocator::SetHandleValue(unsigned __int64 handle, Object *) Line 992	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::FreeHandle(unsigned __int64 handle) Line 884	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTLM(unsigned __int64 i, int isThreadShuttingdown) Line 59	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTable() Line 93	C++	Symbols loaded.
[Inline Frame] coreclr.dll!Thread::DeleteThreadStaticData() Line 7704	C++	Symbols loaded.
coreclr.dll!Thread::OnThreadTerminate(int holdingLock) Line 2956	C++	Symbols loaded.
coreclr.dll!DestroyThread(Thread * th) Line 924	C++	Symbols loaded.
coreclr.dll!ThreadNative::KickOffThread(void * pass) Line 239	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

with an exception which is thrown with the following details:

Exception thrown: read access violation.
**loaderAllocator** was nullptr.
devenv_iJFpiWBvYe

loaderAllocator value from the LOADERALLOCATORREF loaderAllocator = (LOADERALLOCATORREF)ObjectFromHandle(m_hLoaderAllocatorObjectHandle); call is NULL which makes sense, because finalizer thread just disposed data for some of the same LoaderAllocator assemblies.

Note: enabling COR_PRF_MONITOR_MODULE_LOADS CLR profiler flag increases chances for the race condition as it slows down a bit complete loader destruction.

Changes:

I've looked at the following options as a solution to the problem:

  • Null check for loaderAllocator
  • Wait for GC/Finalizers done before killing thread
  • Skip cleaning up thread locals for unloaded loaders

Based on the discussion the acceptable solution would be to:

  • use coop mode to ensure the loader is not collected while we delete thread local handles (we already do it when setting a handle to NULL, so we elevate the scope with a minimal performance consequences)
  • if loader was already collected we do not need to reset handles as they are going to be deallocated anyway further down the loader destruction

@ghostghost added the needs-area-label An area label is needed to ensure this gets routed to the appropriate area owners label May 29, 2024
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@alexey-zakharovalexey-zakharov mentioned this pull request May 29, 2024
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alexey-zakharov marked this pull request as ready for review May 29, 2024 08:34
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@jkotas@davidwrighton checks are green for this PR

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/azp run runtime-coreclr outerloop

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LGTM. Thank you!

@jkotas
jkotas merged commit 8669b74 into dotnet:mainMay 29, 2024
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/backport to release/8.0-staging

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Started backporting to release/8.0-staging: https://github.com/dotnet/runtime/actions/runs/9293876461

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@jkotas backporting to release/8.0-staging failed, the patch most likely resulted in conflicts:

$ git am --3way --ignore-whitespace --keep-non-patch changes.patch
Applying: Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocatorsUsing index info to reconstruct a base tree...M	src/coreclr/vm/threadstatics.cppFalling back to patching base and 3-way merge...Auto-merging src/coreclr/vm/threadstatics.cppCONFLICT (content): Merge conflict in src/coreclr/vm/threadstatics.cpperror: Failed to merge in the changes.hint: Use 'git am --show-current-patch=diff' to see the failed patchhint: When you have resolved this problem, run "git am --continue".hint: If you prefer to skip this patch, run "git am --skip" instead.hint: To restore the original branch and stop patching, run "git am --abort".hint: Disable this message with "git config advice.mergeConflict false"Patch failed at 0001 Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocators
Error: The process '/usr/bin/git' failed with exit code 128

Please backport manually!

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@jkotas an error occurred while backporting to release/8.0-staging, please check the run log for details!

Error: git am failed, most likely due to a merge conflict.

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@alexey-zakharov If you would like to see this backported to .NET 8, could you please submit a PR against release/8.0-staging branch with the merge conflicts resolved?

@alexey-zakharovalexey-zakharov mentioned this pull request May 30, 2024
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@jkotas I've created a backport PR - #102872
thanks for taking the fix in!

@alexey-zakharov
alexey-zakharov deleted the upstream-fix-threadstatic-cleanup branch May 30, 2024 10:37
Ruihan-Yin pushed a commit to Ruihan-Yin/runtime that referenced this pull request May 30, 2024
@alexey-zakharov@Ruihan-Yin
Ensure LoaderAllocator can't be collected while we clean handles on …
44a2f94
…collectible LoaderAllocators (dotnet#102797)
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, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
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}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
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var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

Skip to content
Avoid clearing thread local handles for already unloaded LoaderAllocator - #102797
Merged
jkotas merged 1 commit into
dotnet:mainfrom 
Unity-Technologies:upstream-fix-threadstatic-cleanup
May 29, 2024
Merged
Avoid clearing thread local handles for already unloaded LoaderAllocator#102797
jkotas merged 1 commit into
dotnet:mainfrom 
Unity-Technologies:upstream-fix-threadstatic-cleanup
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@alexey-zakharov
@alexey-zakharovalexey-zakharov
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Motivation:
Fix crash in ThreadLocalBlock::FreeTLM code on thread exit which happens during Assembly unloading when Assembly contains a class with a ThreadStatic variable.
This is a new iteration of #99998 which caused issues on CI.
Details:
There seem to be a race condition between LoaderAllocator cleanup during garbage collection and thread locals cleanup on thread exit. Racing stacks are the following:
ALC/LoaderAllocator cleanup
 coreclr.dll!EEToProfInterfaceImpl::ModuleUnloadStarted(unsigned __int64 moduleId) Line 3735	C++	Symbols loaded.
coreclr.dll!ProfControlBlock::DoProfilerCallbackHelper<int (__cdecl*)(ProfilerInfo *),long (__cdecl*)(EEToProfInterfaceImpl *,unsigned __int64),unsigned __int64>(ProfilerInfo * pProfilerInfo, int(*)(ProfilerInfo *) condition, HRESULT(*)(EEToProfInterfaceImpl *, unsigned __int64) callback, HRESULT * pHR, unsigned __int64 <args_0>) Line 284	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoOneProfilerIteration(ProfilerInfo *) Line 199	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::IterateProfilers(ProfilerCallbackType) Line 207	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoProfilerCallback(ProfilerCallbackType) Line 295	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::ModuleUnloadStarted(unsigned __int64) Line 691	C++	Symbols loaded.
coreclr.dll!Module::Destruct() Line 662	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ClassLoader::FreeModules() Line 1884	C++	Symbols loaded.
coreclr.dll!ClassLoader::~ClassLoader() Line 1946	C++	Symbols loaded.
coreclr.dll!Assembly::Terminate(int) Line 311	C++	Symbols loaded.
coreclr.dll!Assembly::~Assembly() Line 244	C++	Symbols loaded.
coreclr.dll!Assembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
coreclr.dll!DomainAssembly::~DomainAssembly() Line 91	C++	Symbols loaded.
coreclr.dll!DomainAssembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
>	coreclr.dll!LoaderAllocator::GCLoaderAllocators(LoaderAllocator * pOriginalLoaderAllocator) Line 570	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 702	C++	Symbols loaded.
coreclr.dll!LoaderAllocator_Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 718	C++	Symbols loaded.
System.Private.CoreLib.dll!00007ffa9c4308f9()	Unknown	No symbols loaded.
coreclr.dll!FastCallFinalizeWorker() Line 26	Unknown	Symbols loaded.
coreclr.dll!MethodTable::CallFinalizer(Object * obj) Line 4908	C++	Symbols loaded.
[Inline Frame] coreclr.dll!CallFinalizer(Object *) Line 75	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizeAllObjects() Line 110	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadWorker(void * args) Line 354	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_DispatchInner(ManagedThreadCallState *) Line 7222	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchMiddle(ManagedThreadCallState * pCallState) Line 7266	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchOuter(ManagedThreadCallState * pCallState) Line 7425	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_NoADTransition(void(*)(void *)) Line 7494	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase::FinalizerBase(void(*)(void *)) Line 7513	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadStart(void * args) Line 403	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

Thread exit with threadlocal cleanup
>	coreclr.dll!LoaderAllocator::SetHandleValue(unsigned __int64 handle, Object *) Line 992	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::FreeHandle(unsigned __int64 handle) Line 884	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTLM(unsigned __int64 i, int isThreadShuttingdown) Line 59	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTable() Line 93	C++	Symbols loaded.
[Inline Frame] coreclr.dll!Thread::DeleteThreadStaticData() Line 7704	C++	Symbols loaded.
coreclr.dll!Thread::OnThreadTerminate(int holdingLock) Line 2956	C++	Symbols loaded.
coreclr.dll!DestroyThread(Thread * th) Line 924	C++	Symbols loaded.
coreclr.dll!ThreadNative::KickOffThread(void * pass) Line 239	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

with an exception which is thrown with the following details:
Exception thrown: read access violation.
**loaderAllocator** was nullptr.

devenv_iJFpiWBvYe
loaderAllocator value from the LOADERALLOCATORREF loaderAllocator = (LOADERALLOCATORREF)ObjectFromHandle(m_hLoaderAllocatorObjectHandle); call is NULL which makes sense, because finalizer thread just disposed data for some of the same LoaderAllocator assemblies.
Note: enabling COR_PRF_MONITOR_MODULE_LOADS CLR profiler flag increases chances for the race condition as it slows down a bit complete loader destruction.
Changes:
I've looked at the following options as a solution to the problem:
  • Null check for loaderAllocator
  • Wait for GC/Finalizers done before killing thread
  • Skip cleaning up thread locals for unloaded loaders
Based on the discussion the acceptable solution would be to:
  • use coop mode to ensure the loader is not collected while we delete thread local handles (we already do it when setting a handle to NULL, so we elevate the scope with a minimal performance consequences)
  • if loader was already collected we do not need to reset handles as they are going to be deallocated anyway further down the loader destruction
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@jkotas@davidwrighton checks are green for this PR
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/azp run runtime-coreclr outerloop
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LGTM. Thank you!
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/backport to release/8.0-staging
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Started backporting to release/8.0-staging: https://github.com/dotnet/runtime/actions/runs/9293876461
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@jkotas backporting to release/8.0-staging failed, the patch most likely resulted in conflicts:
$ git am --3way --ignore-whitespace --keep-non-patch changes.patch
Applying: Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocatorsUsing index info to reconstruct a base tree...M	src/coreclr/vm/threadstatics.cppFalling back to patching base and 3-way merge...Auto-merging src/coreclr/vm/threadstatics.cppCONFLICT (content): Merge conflict in src/coreclr/vm/threadstatics.cpperror: Failed to merge in the changes.hint: Use 'git am --show-current-patch=diff' to see the failed patchhint: When you have resolved this problem, run "git am --continue".hint: If you prefer to skip this patch, run "git am --skip" instead.hint: To restore the original branch and stop patching, run "git am --abort".hint: Disable this message with "git config advice.mergeConflict false"Patch failed at 0001 Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocators
Error: The process '/usr/bin/git' failed with exit code 128
Please backport manually!
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@jkotas an error occurred while backporting to release/8.0-staging, please check the run log for details!
Error: git am failed, most likely due to a merge conflict.
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@alexey-zakharov If you would like to see this backported to .NET 8, could you please submit a PR against release/8.0-staging branch with the merge conflicts resolved?
@alexey-zakharovalexey-zakharov
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@jkotas I've created a backport PR - #102872

thanks for taking the fix in!
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Ensure LoaderAllocator can't be collected while we clean handles on …
44a2f94
…collectible LoaderAllocators (dotnet#102797)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Avoid clearing thread local handles for already unloaded LoaderAllocator - #102797
Merged
jkotas merged 1 commit into
dotnet:mainfrom 
Unity-Technologies:upstream-fix-threadstatic-cleanup
May 29, 2024
Merged
Avoid clearing thread local handles for already unloaded LoaderAllocator#102797
jkotas merged 1 commit into
dotnet:mainfrom 
Unity-Technologies:upstream-fix-threadstatic-cleanup
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Motivation:
Fix crash in ThreadLocalBlock::FreeTLM code on thread exit which happens during Assembly unloading when Assembly contains a class with a ThreadStatic variable.
This is a new iteration of #99998 which caused issues on CI.
Details:
There seem to be a race condition between LoaderAllocator cleanup during garbage collection and thread locals cleanup on thread exit. Racing stacks are the following:
ALC/LoaderAllocator cleanup
 coreclr.dll!EEToProfInterfaceImpl::ModuleUnloadStarted(unsigned __int64 moduleId) Line 3735	C++	Symbols loaded.
coreclr.dll!ProfControlBlock::DoProfilerCallbackHelper<int (__cdecl*)(ProfilerInfo *),long (__cdecl*)(EEToProfInterfaceImpl *,unsigned __int64),unsigned __int64>(ProfilerInfo * pProfilerInfo, int(*)(ProfilerInfo *) condition, HRESULT(*)(EEToProfInterfaceImpl *, unsigned __int64) callback, HRESULT * pHR, unsigned __int64 <args_0>) Line 284	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoOneProfilerIteration(ProfilerInfo *) Line 199	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::IterateProfilers(ProfilerCallbackType) Line 207	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoProfilerCallback(ProfilerCallbackType) Line 295	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::ModuleUnloadStarted(unsigned __int64) Line 691	C++	Symbols loaded.
coreclr.dll!Module::Destruct() Line 662	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ClassLoader::FreeModules() Line 1884	C++	Symbols loaded.
coreclr.dll!ClassLoader::~ClassLoader() Line 1946	C++	Symbols loaded.
coreclr.dll!Assembly::Terminate(int) Line 311	C++	Symbols loaded.
coreclr.dll!Assembly::~Assembly() Line 244	C++	Symbols loaded.
coreclr.dll!Assembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
coreclr.dll!DomainAssembly::~DomainAssembly() Line 91	C++	Symbols loaded.
coreclr.dll!DomainAssembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
>	coreclr.dll!LoaderAllocator::GCLoaderAllocators(LoaderAllocator * pOriginalLoaderAllocator) Line 570	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 702	C++	Symbols loaded.
coreclr.dll!LoaderAllocator_Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 718	C++	Symbols loaded.
System.Private.CoreLib.dll!00007ffa9c4308f9()	Unknown	No symbols loaded.
coreclr.dll!FastCallFinalizeWorker() Line 26	Unknown	Symbols loaded.
coreclr.dll!MethodTable::CallFinalizer(Object * obj) Line 4908	C++	Symbols loaded.
[Inline Frame] coreclr.dll!CallFinalizer(Object *) Line 75	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizeAllObjects() Line 110	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadWorker(void * args) Line 354	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_DispatchInner(ManagedThreadCallState *) Line 7222	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchMiddle(ManagedThreadCallState * pCallState) Line 7266	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchOuter(ManagedThreadCallState * pCallState) Line 7425	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_NoADTransition(void(*)(void *)) Line 7494	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase::FinalizerBase(void(*)(void *)) Line 7513	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadStart(void * args) Line 403	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

Thread exit with threadlocal cleanup
>	coreclr.dll!LoaderAllocator::SetHandleValue(unsigned __int64 handle, Object *) Line 992	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::FreeHandle(unsigned __int64 handle) Line 884	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTLM(unsigned __int64 i, int isThreadShuttingdown) Line 59	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTable() Line 93	C++	Symbols loaded.
[Inline Frame] coreclr.dll!Thread::DeleteThreadStaticData() Line 7704	C++	Symbols loaded.
coreclr.dll!Thread::OnThreadTerminate(int holdingLock) Line 2956	C++	Symbols loaded.
coreclr.dll!DestroyThread(Thread * th) Line 924	C++	Symbols loaded.
coreclr.dll!ThreadNative::KickOffThread(void * pass) Line 239	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

with an exception which is thrown with the following details:
Exception thrown: read access violation.
**loaderAllocator** was nullptr.

devenv_iJFpiWBvYe
loaderAllocator value from the LOADERALLOCATORREF loaderAllocator = (LOADERALLOCATORREF)ObjectFromHandle(m_hLoaderAllocatorObjectHandle); call is NULL which makes sense, because finalizer thread just disposed data for some of the same LoaderAllocator assemblies.
Note: enabling COR_PRF_MONITOR_MODULE_LOADS CLR profiler flag increases chances for the race condition as it slows down a bit complete loader destruction.
Changes:
I've looked at the following options as a solution to the problem:
  • Null check for loaderAllocator
  • Wait for GC/Finalizers done before killing thread
  • Skip cleaning up thread locals for unloaded loaders
Based on the discussion the acceptable solution would be to:
  • use coop mode to ensure the loader is not collected while we delete thread local handles (we already do it when setting a handle to NULL, so we elevate the scope with a minimal performance consequences)
  • if loader was already collected we do not need to reset handles as they are going to be deallocated anyway further down the loader destruction
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/azp run runtime-coreclr outerloop
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LGTM. Thank you!
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/backport to release/8.0-staging
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Started backporting to release/8.0-staging: https://github.com/dotnet/runtime/actions/runs/9293876461
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@jkotas backporting to release/8.0-staging failed, the patch most likely resulted in conflicts:
$ git am --3way --ignore-whitespace --keep-non-patch changes.patch
Applying: Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocatorsUsing index info to reconstruct a base tree...M	src/coreclr/vm/threadstatics.cppFalling back to patching base and 3-way merge...Auto-merging src/coreclr/vm/threadstatics.cppCONFLICT (content): Merge conflict in src/coreclr/vm/threadstatics.cpperror: Failed to merge in the changes.hint: Use 'git am --show-current-patch=diff' to see the failed patchhint: When you have resolved this problem, run "git am --continue".hint: If you prefer to skip this patch, run "git am --skip" instead.hint: To restore the original branch and stop patching, run "git am --abort".hint: Disable this message with "git config advice.mergeConflict false"Patch failed at 0001 Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocators
Error: The process '/usr/bin/git' failed with exit code 128
Please backport manually!
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@jkotas an error occurred while backporting to release/8.0-staging, please check the run log for details!
Error: git am failed, most likely due to a merge conflict.
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@alexey-zakharov If you would like to see this backported to .NET 8, could you please submit a PR against release/8.0-staging branch with the merge conflicts resolved?
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@jkotas I've created a backport PR - #102872

thanks for taking the fix in!
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@alexey-zakharov@Ruihan-Yin
Ensure LoaderAllocator can't be collected while we clean handles on …
44a2f94
…collectible LoaderAllocators (dotnet#102797)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Avoid clearing thread local handles for already unloaded LoaderAllocator - #102797
Merged
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Unity-Technologies:upstream-fix-threadstatic-cleanup
May 29, 2024
Merged
Avoid clearing thread local handles for already unloaded LoaderAllocator#102797
jkotas merged 1 commit into
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Unity-Technologies:upstream-fix-threadstatic-cleanup
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Motivation:
Fix crash in ThreadLocalBlock::FreeTLM code on thread exit which happens during Assembly unloading when Assembly contains a class with a ThreadStatic variable.
This is a new iteration of #99998 which caused issues on CI.
Details:
There seem to be a race condition between LoaderAllocator cleanup during garbage collection and thread locals cleanup on thread exit. Racing stacks are the following:
ALC/LoaderAllocator cleanup
 coreclr.dll!EEToProfInterfaceImpl::ModuleUnloadStarted(unsigned __int64 moduleId) Line 3735	C++	Symbols loaded.
coreclr.dll!ProfControlBlock::DoProfilerCallbackHelper<int (__cdecl*)(ProfilerInfo *),long (__cdecl*)(EEToProfInterfaceImpl *,unsigned __int64),unsigned __int64>(ProfilerInfo * pProfilerInfo, int(*)(ProfilerInfo *) condition, HRESULT(*)(EEToProfInterfaceImpl *, unsigned __int64) callback, HRESULT * pHR, unsigned __int64 <args_0>) Line 284	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoOneProfilerIteration(ProfilerInfo *) Line 199	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::IterateProfilers(ProfilerCallbackType) Line 207	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoProfilerCallback(ProfilerCallbackType) Line 295	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::ModuleUnloadStarted(unsigned __int64) Line 691	C++	Symbols loaded.
coreclr.dll!Module::Destruct() Line 662	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ClassLoader::FreeModules() Line 1884	C++	Symbols loaded.
coreclr.dll!ClassLoader::~ClassLoader() Line 1946	C++	Symbols loaded.
coreclr.dll!Assembly::Terminate(int) Line 311	C++	Symbols loaded.
coreclr.dll!Assembly::~Assembly() Line 244	C++	Symbols loaded.
coreclr.dll!Assembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
coreclr.dll!DomainAssembly::~DomainAssembly() Line 91	C++	Symbols loaded.
coreclr.dll!DomainAssembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
>	coreclr.dll!LoaderAllocator::GCLoaderAllocators(LoaderAllocator * pOriginalLoaderAllocator) Line 570	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 702	C++	Symbols loaded.
coreclr.dll!LoaderAllocator_Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 718	C++	Symbols loaded.
System.Private.CoreLib.dll!00007ffa9c4308f9()	Unknown	No symbols loaded.
coreclr.dll!FastCallFinalizeWorker() Line 26	Unknown	Symbols loaded.
coreclr.dll!MethodTable::CallFinalizer(Object * obj) Line 4908	C++	Symbols loaded.
[Inline Frame] coreclr.dll!CallFinalizer(Object *) Line 75	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizeAllObjects() Line 110	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadWorker(void * args) Line 354	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_DispatchInner(ManagedThreadCallState *) Line 7222	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchMiddle(ManagedThreadCallState * pCallState) Line 7266	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchOuter(ManagedThreadCallState * pCallState) Line 7425	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_NoADTransition(void(*)(void *)) Line 7494	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase::FinalizerBase(void(*)(void *)) Line 7513	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadStart(void * args) Line 403	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

Thread exit with threadlocal cleanup
>	coreclr.dll!LoaderAllocator::SetHandleValue(unsigned __int64 handle, Object *) Line 992	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::FreeHandle(unsigned __int64 handle) Line 884	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTLM(unsigned __int64 i, int isThreadShuttingdown) Line 59	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTable() Line 93	C++	Symbols loaded.
[Inline Frame] coreclr.dll!Thread::DeleteThreadStaticData() Line 7704	C++	Symbols loaded.
coreclr.dll!Thread::OnThreadTerminate(int holdingLock) Line 2956	C++	Symbols loaded.
coreclr.dll!DestroyThread(Thread * th) Line 924	C++	Symbols loaded.
coreclr.dll!ThreadNative::KickOffThread(void * pass) Line 239	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

with an exception which is thrown with the following details:
Exception thrown: read access violation.
**loaderAllocator** was nullptr.

devenv_iJFpiWBvYe
loaderAllocator value from the LOADERALLOCATORREF loaderAllocator = (LOADERALLOCATORREF)ObjectFromHandle(m_hLoaderAllocatorObjectHandle); call is NULL which makes sense, because finalizer thread just disposed data for some of the same LoaderAllocator assemblies.
Note: enabling COR_PRF_MONITOR_MODULE_LOADS CLR profiler flag increases chances for the race condition as it slows down a bit complete loader destruction.
Changes:
I've looked at the following options as a solution to the problem:
  • Null check for loaderAllocator
  • Wait for GC/Finalizers done before killing thread
  • Skip cleaning up thread locals for unloaded loaders
Based on the discussion the acceptable solution would be to:
  • use coop mode to ensure the loader is not collected while we delete thread local handles (we already do it when setting a handle to NULL, so we elevate the scope with a minimal performance consequences)
  • if loader was already collected we do not need to reset handles as they are going to be deallocated anyway further down the loader destruction
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/azp run runtime-coreclr outerloop
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LGTM. Thank you!
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/backport to release/8.0-staging
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Started backporting to release/8.0-staging: https://github.com/dotnet/runtime/actions/runs/9293876461
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@jkotas backporting to release/8.0-staging failed, the patch most likely resulted in conflicts:
$ git am --3way --ignore-whitespace --keep-non-patch changes.patch
Applying: Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocatorsUsing index info to reconstruct a base tree...M	src/coreclr/vm/threadstatics.cppFalling back to patching base and 3-way merge...Auto-merging src/coreclr/vm/threadstatics.cppCONFLICT (content): Merge conflict in src/coreclr/vm/threadstatics.cpperror: Failed to merge in the changes.hint: Use 'git am --show-current-patch=diff' to see the failed patchhint: When you have resolved this problem, run "git am --continue".hint: If you prefer to skip this patch, run "git am --skip" instead.hint: To restore the original branch and stop patching, run "git am --abort".hint: Disable this message with "git config advice.mergeConflict false"Patch failed at 0001 Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocators
Error: The process '/usr/bin/git' failed with exit code 128
Please backport manually!
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@jkotas an error occurred while backporting to release/8.0-staging, please check the run log for details!
Error: git am failed, most likely due to a merge conflict.
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@alexey-zakharov If you would like to see this backported to .NET 8, could you please submit a PR against release/8.0-staging branch with the merge conflicts resolved?
@alexey-zakharovalexey-zakharov
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@jkotas I've created a backport PR - #102872

thanks for taking the fix in!
@alexey-zakharov
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@alexey-zakharov@Ruihan-Yin
Ensure LoaderAllocator can't be collected while we clean handles on …
44a2f94
…collectible LoaderAllocators (dotnet#102797)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
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var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

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Avoid clearing thread local handles for already unloaded LoaderAllocator - #102797
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Unity-Technologies:upstream-fix-threadstatic-cleanup
May 29, 2024
Merged
Avoid clearing thread local handles for already unloaded LoaderAllocator#102797
jkotas merged 1 commit into
dotnet:mainfrom 
Unity-Technologies:upstream-fix-threadstatic-cleanup
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Motivation:
Fix crash in ThreadLocalBlock::FreeTLM code on thread exit which happens during Assembly unloading when Assembly contains a class with a ThreadStatic variable.
This is a new iteration of #99998 which caused issues on CI.
Details:
There seem to be a race condition between LoaderAllocator cleanup during garbage collection and thread locals cleanup on thread exit. Racing stacks are the following:
ALC/LoaderAllocator cleanup
 coreclr.dll!EEToProfInterfaceImpl::ModuleUnloadStarted(unsigned __int64 moduleId) Line 3735	C++	Symbols loaded.
coreclr.dll!ProfControlBlock::DoProfilerCallbackHelper<int (__cdecl*)(ProfilerInfo *),long (__cdecl*)(EEToProfInterfaceImpl *,unsigned __int64),unsigned __int64>(ProfilerInfo * pProfilerInfo, int(*)(ProfilerInfo *) condition, HRESULT(*)(EEToProfInterfaceImpl *, unsigned __int64) callback, HRESULT * pHR, unsigned __int64 <args_0>) Line 284	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoOneProfilerIteration(ProfilerInfo *) Line 199	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::IterateProfilers(ProfilerCallbackType) Line 207	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoProfilerCallback(ProfilerCallbackType) Line 295	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::ModuleUnloadStarted(unsigned __int64) Line 691	C++	Symbols loaded.
coreclr.dll!Module::Destruct() Line 662	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ClassLoader::FreeModules() Line 1884	C++	Symbols loaded.
coreclr.dll!ClassLoader::~ClassLoader() Line 1946	C++	Symbols loaded.
coreclr.dll!Assembly::Terminate(int) Line 311	C++	Symbols loaded.
coreclr.dll!Assembly::~Assembly() Line 244	C++	Symbols loaded.
coreclr.dll!Assembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
coreclr.dll!DomainAssembly::~DomainAssembly() Line 91	C++	Symbols loaded.
coreclr.dll!DomainAssembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
>	coreclr.dll!LoaderAllocator::GCLoaderAllocators(LoaderAllocator * pOriginalLoaderAllocator) Line 570	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 702	C++	Symbols loaded.
coreclr.dll!LoaderAllocator_Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 718	C++	Symbols loaded.
System.Private.CoreLib.dll!00007ffa9c4308f9()	Unknown	No symbols loaded.
coreclr.dll!FastCallFinalizeWorker() Line 26	Unknown	Symbols loaded.
coreclr.dll!MethodTable::CallFinalizer(Object * obj) Line 4908	C++	Symbols loaded.
[Inline Frame] coreclr.dll!CallFinalizer(Object *) Line 75	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizeAllObjects() Line 110	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadWorker(void * args) Line 354	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_DispatchInner(ManagedThreadCallState *) Line 7222	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchMiddle(ManagedThreadCallState * pCallState) Line 7266	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchOuter(ManagedThreadCallState * pCallState) Line 7425	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_NoADTransition(void(*)(void *)) Line 7494	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase::FinalizerBase(void(*)(void *)) Line 7513	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadStart(void * args) Line 403	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

Thread exit with threadlocal cleanup
>	coreclr.dll!LoaderAllocator::SetHandleValue(unsigned __int64 handle, Object *) Line 992	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::FreeHandle(unsigned __int64 handle) Line 884	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTLM(unsigned __int64 i, int isThreadShuttingdown) Line 59	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTable() Line 93	C++	Symbols loaded.
[Inline Frame] coreclr.dll!Thread::DeleteThreadStaticData() Line 7704	C++	Symbols loaded.
coreclr.dll!Thread::OnThreadTerminate(int holdingLock) Line 2956	C++	Symbols loaded.
coreclr.dll!DestroyThread(Thread * th) Line 924	C++	Symbols loaded.
coreclr.dll!ThreadNative::KickOffThread(void * pass) Line 239	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

with an exception which is thrown with the following details:
Exception thrown: read access violation.
**loaderAllocator** was nullptr.

devenv_iJFpiWBvYe
loaderAllocator value from the LOADERALLOCATORREF loaderAllocator = (LOADERALLOCATORREF)ObjectFromHandle(m_hLoaderAllocatorObjectHandle); call is NULL which makes sense, because finalizer thread just disposed data for some of the same LoaderAllocator assemblies.
Note: enabling COR_PRF_MONITOR_MODULE_LOADS CLR profiler flag increases chances for the race condition as it slows down a bit complete loader destruction.
Changes:
I've looked at the following options as a solution to the problem:
  • Null check for loaderAllocator
  • Wait for GC/Finalizers done before killing thread
  • Skip cleaning up thread locals for unloaded loaders
Based on the discussion the acceptable solution would be to:
  • use coop mode to ensure the loader is not collected while we delete thread local handles (we already do it when setting a handle to NULL, so we elevate the scope with a minimal performance consequences)
  • if loader was already collected we do not need to reset handles as they are going to be deallocated anyway further down the loader destruction
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/azp run runtime-coreclr outerloop
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LGTM. Thank you!
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/backport to release/8.0-staging
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Started backporting to release/8.0-staging: https://github.com/dotnet/runtime/actions/runs/9293876461
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@jkotas backporting to release/8.0-staging failed, the patch most likely resulted in conflicts:
$ git am --3way --ignore-whitespace --keep-non-patch changes.patch
Applying: Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocatorsUsing index info to reconstruct a base tree...M	src/coreclr/vm/threadstatics.cppFalling back to patching base and 3-way merge...Auto-merging src/coreclr/vm/threadstatics.cppCONFLICT (content): Merge conflict in src/coreclr/vm/threadstatics.cpperror: Failed to merge in the changes.hint: Use 'git am --show-current-patch=diff' to see the failed patchhint: When you have resolved this problem, run "git am --continue".hint: If you prefer to skip this patch, run "git am --skip" instead.hint: To restore the original branch and stop patching, run "git am --abort".hint: Disable this message with "git config advice.mergeConflict false"Patch failed at 0001 Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocators
Error: The process '/usr/bin/git' failed with exit code 128
Please backport manually!
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@jkotas an error occurred while backporting to release/8.0-staging, please check the run log for details!
Error: git am failed, most likely due to a merge conflict.
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@alexey-zakharov If you would like to see this backported to .NET 8, could you please submit a PR against release/8.0-staging branch with the merge conflicts resolved?
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@jkotas I've created a backport PR - #102872

thanks for taking the fix in!
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@alexey-zakharov@Ruihan-Yin
Ensure LoaderAllocator can't be collected while we clean handles on …
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…collectible LoaderAllocators (dotnet#102797)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Avoid clearing thread local handles for already unloaded LoaderAllocator - #102797
Merged
jkotas merged 1 commit into
dotnet:mainfrom 
Unity-Technologies:upstream-fix-threadstatic-cleanup
May 29, 2024
Merged
Avoid clearing thread local handles for already unloaded LoaderAllocator#102797
jkotas merged 1 commit into
dotnet:mainfrom 
Unity-Technologies:upstream-fix-threadstatic-cleanup
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@alexey-zakharov
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Motivation:
Fix crash in ThreadLocalBlock::FreeTLM code on thread exit which happens during Assembly unloading when Assembly contains a class with a ThreadStatic variable.
This is a new iteration of #99998 which caused issues on CI.
Details:
There seem to be a race condition between LoaderAllocator cleanup during garbage collection and thread locals cleanup on thread exit. Racing stacks are the following:
ALC/LoaderAllocator cleanup
 coreclr.dll!EEToProfInterfaceImpl::ModuleUnloadStarted(unsigned __int64 moduleId) Line 3735	C++	Symbols loaded.
coreclr.dll!ProfControlBlock::DoProfilerCallbackHelper<int (__cdecl*)(ProfilerInfo *),long (__cdecl*)(EEToProfInterfaceImpl *,unsigned __int64),unsigned __int64>(ProfilerInfo * pProfilerInfo, int(*)(ProfilerInfo *) condition, HRESULT(*)(EEToProfInterfaceImpl *, unsigned __int64) callback, HRESULT * pHR, unsigned __int64 <args_0>) Line 284	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoOneProfilerIteration(ProfilerInfo *) Line 199	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::IterateProfilers(ProfilerCallbackType) Line 207	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoProfilerCallback(ProfilerCallbackType) Line 295	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::ModuleUnloadStarted(unsigned __int64) Line 691	C++	Symbols loaded.
coreclr.dll!Module::Destruct() Line 662	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ClassLoader::FreeModules() Line 1884	C++	Symbols loaded.
coreclr.dll!ClassLoader::~ClassLoader() Line 1946	C++	Symbols loaded.
coreclr.dll!Assembly::Terminate(int) Line 311	C++	Symbols loaded.
coreclr.dll!Assembly::~Assembly() Line 244	C++	Symbols loaded.
coreclr.dll!Assembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
coreclr.dll!DomainAssembly::~DomainAssembly() Line 91	C++	Symbols loaded.
coreclr.dll!DomainAssembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
>	coreclr.dll!LoaderAllocator::GCLoaderAllocators(LoaderAllocator * pOriginalLoaderAllocator) Line 570	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 702	C++	Symbols loaded.
coreclr.dll!LoaderAllocator_Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 718	C++	Symbols loaded.
System.Private.CoreLib.dll!00007ffa9c4308f9()	Unknown	No symbols loaded.
coreclr.dll!FastCallFinalizeWorker() Line 26	Unknown	Symbols loaded.
coreclr.dll!MethodTable::CallFinalizer(Object * obj) Line 4908	C++	Symbols loaded.
[Inline Frame] coreclr.dll!CallFinalizer(Object *) Line 75	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizeAllObjects() Line 110	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadWorker(void * args) Line 354	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_DispatchInner(ManagedThreadCallState *) Line 7222	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchMiddle(ManagedThreadCallState * pCallState) Line 7266	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchOuter(ManagedThreadCallState * pCallState) Line 7425	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_NoADTransition(void(*)(void *)) Line 7494	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase::FinalizerBase(void(*)(void *)) Line 7513	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadStart(void * args) Line 403	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

Thread exit with threadlocal cleanup
>	coreclr.dll!LoaderAllocator::SetHandleValue(unsigned __int64 handle, Object *) Line 992	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::FreeHandle(unsigned __int64 handle) Line 884	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTLM(unsigned __int64 i, int isThreadShuttingdown) Line 59	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTable() Line 93	C++	Symbols loaded.
[Inline Frame] coreclr.dll!Thread::DeleteThreadStaticData() Line 7704	C++	Symbols loaded.
coreclr.dll!Thread::OnThreadTerminate(int holdingLock) Line 2956	C++	Symbols loaded.
coreclr.dll!DestroyThread(Thread * th) Line 924	C++	Symbols loaded.
coreclr.dll!ThreadNative::KickOffThread(void * pass) Line 239	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

with an exception which is thrown with the following details:
Exception thrown: read access violation.
**loaderAllocator** was nullptr.

devenv_iJFpiWBvYe
loaderAllocator value from the LOADERALLOCATORREF loaderAllocator = (LOADERALLOCATORREF)ObjectFromHandle(m_hLoaderAllocatorObjectHandle); call is NULL which makes sense, because finalizer thread just disposed data for some of the same LoaderAllocator assemblies.
Note: enabling COR_PRF_MONITOR_MODULE_LOADS CLR profiler flag increases chances for the race condition as it slows down a bit complete loader destruction.
Changes:
I've looked at the following options as a solution to the problem:
  • Null check for loaderAllocator
  • Wait for GC/Finalizers done before killing thread
  • Skip cleaning up thread locals for unloaded loaders
Based on the discussion the acceptable solution would be to:
  • use coop mode to ensure the loader is not collected while we delete thread local handles (we already do it when setting a handle to NULL, so we elevate the scope with a minimal performance consequences)
  • if loader was already collected we do not need to reset handles as they are going to be deallocated anyway further down the loader destruction
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@jkotas@davidwrighton checks are green for this PR
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/azp run runtime-coreclr outerloop
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LGTM. Thank you!
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/backport to release/8.0-staging
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Started backporting to release/8.0-staging: https://github.com/dotnet/runtime/actions/runs/9293876461
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@jkotas backporting to release/8.0-staging failed, the patch most likely resulted in conflicts:
$ git am --3way --ignore-whitespace --keep-non-patch changes.patch
Applying: Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocatorsUsing index info to reconstruct a base tree...M	src/coreclr/vm/threadstatics.cppFalling back to patching base and 3-way merge...Auto-merging src/coreclr/vm/threadstatics.cppCONFLICT (content): Merge conflict in src/coreclr/vm/threadstatics.cpperror: Failed to merge in the changes.hint: Use 'git am --show-current-patch=diff' to see the failed patchhint: When you have resolved this problem, run "git am --continue".hint: If you prefer to skip this patch, run "git am --skip" instead.hint: To restore the original branch and stop patching, run "git am --abort".hint: Disable this message with "git config advice.mergeConflict false"Patch failed at 0001 Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocators
Error: The process '/usr/bin/git' failed with exit code 128
Please backport manually!
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@jkotas an error occurred while backporting to release/8.0-staging, please check the run log for details!
Error: git am failed, most likely due to a merge conflict.
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@alexey-zakharov If you would like to see this backported to .NET 8, could you please submit a PR against release/8.0-staging branch with the merge conflicts resolved?
@alexey-zakharovalexey-zakharov
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@jkotas I've created a backport PR - #102872

thanks for taking the fix in!
@alexey-zakharov
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upstream-fix-threadstatic-cleanup

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May 30, 2024 10:37
Ruihan-Yin pushed a commit
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@alexey-zakharov@Ruihan-Yin
Ensure LoaderAllocator can't be collected while we clean handles on …
44a2f94
…collectible LoaderAllocators (dotnet#102797)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
Avoid clearing thread local handles for already unloaded LoaderAllocator - #102797
Merged
jkotas merged 1 commit into
dotnet:mainfrom 
Unity-Technologies:upstream-fix-threadstatic-cleanup
May 29, 2024
Merged
Avoid clearing thread local handles for already unloaded LoaderAllocator#102797
jkotas merged 1 commit into
dotnet:mainfrom 
Unity-Technologies:upstream-fix-threadstatic-cleanup
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Motivation:
Fix crash in ThreadLocalBlock::FreeTLM code on thread exit which happens during Assembly unloading when Assembly contains a class with a ThreadStatic variable.
This is a new iteration of #99998 which caused issues on CI.
Details:
There seem to be a race condition between LoaderAllocator cleanup during garbage collection and thread locals cleanup on thread exit. Racing stacks are the following:
ALC/LoaderAllocator cleanup
 coreclr.dll!EEToProfInterfaceImpl::ModuleUnloadStarted(unsigned __int64 moduleId) Line 3735	C++	Symbols loaded.
coreclr.dll!ProfControlBlock::DoProfilerCallbackHelper<int (__cdecl*)(ProfilerInfo *),long (__cdecl*)(EEToProfInterfaceImpl *,unsigned __int64),unsigned __int64>(ProfilerInfo * pProfilerInfo, int(*)(ProfilerInfo *) condition, HRESULT(*)(EEToProfInterfaceImpl *, unsigned __int64) callback, HRESULT * pHR, unsigned __int64 <args_0>) Line 284	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoOneProfilerIteration(ProfilerInfo *) Line 199	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::IterateProfilers(ProfilerCallbackType) Line 207	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoProfilerCallback(ProfilerCallbackType) Line 295	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::ModuleUnloadStarted(unsigned __int64) Line 691	C++	Symbols loaded.
coreclr.dll!Module::Destruct() Line 662	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ClassLoader::FreeModules() Line 1884	C++	Symbols loaded.
coreclr.dll!ClassLoader::~ClassLoader() Line 1946	C++	Symbols loaded.
coreclr.dll!Assembly::Terminate(int) Line 311	C++	Symbols loaded.
coreclr.dll!Assembly::~Assembly() Line 244	C++	Symbols loaded.
coreclr.dll!Assembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
coreclr.dll!DomainAssembly::~DomainAssembly() Line 91	C++	Symbols loaded.
coreclr.dll!DomainAssembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
>	coreclr.dll!LoaderAllocator::GCLoaderAllocators(LoaderAllocator * pOriginalLoaderAllocator) Line 570	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 702	C++	Symbols loaded.
coreclr.dll!LoaderAllocator_Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 718	C++	Symbols loaded.
System.Private.CoreLib.dll!00007ffa9c4308f9()	Unknown	No symbols loaded.
coreclr.dll!FastCallFinalizeWorker() Line 26	Unknown	Symbols loaded.
coreclr.dll!MethodTable::CallFinalizer(Object * obj) Line 4908	C++	Symbols loaded.
[Inline Frame] coreclr.dll!CallFinalizer(Object *) Line 75	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizeAllObjects() Line 110	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadWorker(void * args) Line 354	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_DispatchInner(ManagedThreadCallState *) Line 7222	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchMiddle(ManagedThreadCallState * pCallState) Line 7266	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchOuter(ManagedThreadCallState * pCallState) Line 7425	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_NoADTransition(void(*)(void *)) Line 7494	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase::FinalizerBase(void(*)(void *)) Line 7513	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadStart(void * args) Line 403	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

Thread exit with threadlocal cleanup
>	coreclr.dll!LoaderAllocator::SetHandleValue(unsigned __int64 handle, Object *) Line 992	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::FreeHandle(unsigned __int64 handle) Line 884	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTLM(unsigned __int64 i, int isThreadShuttingdown) Line 59	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTable() Line 93	C++	Symbols loaded.
[Inline Frame] coreclr.dll!Thread::DeleteThreadStaticData() Line 7704	C++	Symbols loaded.
coreclr.dll!Thread::OnThreadTerminate(int holdingLock) Line 2956	C++	Symbols loaded.
coreclr.dll!DestroyThread(Thread * th) Line 924	C++	Symbols loaded.
coreclr.dll!ThreadNative::KickOffThread(void * pass) Line 239	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

with an exception which is thrown with the following details:
Exception thrown: read access violation.
**loaderAllocator** was nullptr.

devenv_iJFpiWBvYe
loaderAllocator value from the LOADERALLOCATORREF loaderAllocator = (LOADERALLOCATORREF)ObjectFromHandle(m_hLoaderAllocatorObjectHandle); call is NULL which makes sense, because finalizer thread just disposed data for some of the same LoaderAllocator assemblies.
Note: enabling COR_PRF_MONITOR_MODULE_LOADS CLR profiler flag increases chances for the race condition as it slows down a bit complete loader destruction.
Changes:
I've looked at the following options as a solution to the problem:
  • Null check for loaderAllocator
  • Wait for GC/Finalizers done before killing thread
  • Skip cleaning up thread locals for unloaded loaders
Based on the discussion the acceptable solution would be to:
  • use coop mode to ensure the loader is not collected while we delete thread local handles (we already do it when setting a handle to NULL, so we elevate the scope with a minimal performance consequences)
  • if loader was already collected we do not need to reset handles as they are going to be deallocated anyway further down the loader destruction
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/azp run runtime-coreclr outerloop
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LGTM. Thank you!
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/backport to release/8.0-staging
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Started backporting to release/8.0-staging: https://github.com/dotnet/runtime/actions/runs/9293876461
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@jkotas backporting to release/8.0-staging failed, the patch most likely resulted in conflicts:
$ git am --3way --ignore-whitespace --keep-non-patch changes.patch
Applying: Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocatorsUsing index info to reconstruct a base tree...M	src/coreclr/vm/threadstatics.cppFalling back to patching base and 3-way merge...Auto-merging src/coreclr/vm/threadstatics.cppCONFLICT (content): Merge conflict in src/coreclr/vm/threadstatics.cpperror: Failed to merge in the changes.hint: Use 'git am --show-current-patch=diff' to see the failed patchhint: When you have resolved this problem, run "git am --continue".hint: If you prefer to skip this patch, run "git am --skip" instead.hint: To restore the original branch and stop patching, run "git am --abort".hint: Disable this message with "git config advice.mergeConflict false"Patch failed at 0001 Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocators
Error: The process '/usr/bin/git' failed with exit code 128
Please backport manually!
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@jkotas an error occurred while backporting to release/8.0-staging, please check the run log for details!
Error: git am failed, most likely due to a merge conflict.
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@alexey-zakharov If you would like to see this backported to .NET 8, could you please submit a PR against release/8.0-staging branch with the merge conflicts resolved?
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@jkotas I've created a backport PR - #102872

thanks for taking the fix in!
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Ensure LoaderAllocator can't be collected while we clean handles on …
44a2f94
…collectible LoaderAllocators (dotnet#102797)
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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Avoid clearing thread local handles for already unloaded LoaderAllocator - #102797
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Unity-Technologies:upstream-fix-threadstatic-cleanup
May 29, 2024
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Avoid clearing thread local handles for already unloaded LoaderAllocator#102797
jkotas merged 1 commit into
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Unity-Technologies:upstream-fix-threadstatic-cleanup
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Motivation:
Fix crash in ThreadLocalBlock::FreeTLM code on thread exit which happens during Assembly unloading when Assembly contains a class with a ThreadStatic variable.
This is a new iteration of #99998 which caused issues on CI.
Details:
There seem to be a race condition between LoaderAllocator cleanup during garbage collection and thread locals cleanup on thread exit. Racing stacks are the following:
ALC/LoaderAllocator cleanup
 coreclr.dll!EEToProfInterfaceImpl::ModuleUnloadStarted(unsigned __int64 moduleId) Line 3735	C++	Symbols loaded.
coreclr.dll!ProfControlBlock::DoProfilerCallbackHelper<int (__cdecl*)(ProfilerInfo *),long (__cdecl*)(EEToProfInterfaceImpl *,unsigned __int64),unsigned __int64>(ProfilerInfo * pProfilerInfo, int(*)(ProfilerInfo *) condition, HRESULT(*)(EEToProfInterfaceImpl *, unsigned __int64) callback, HRESULT * pHR, unsigned __int64 <args_0>) Line 284	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoOneProfilerIteration(ProfilerInfo *) Line 199	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::IterateProfilers(ProfilerCallbackType) Line 207	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::DoProfilerCallback(ProfilerCallbackType) Line 295	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ProfControlBlock::ModuleUnloadStarted(unsigned __int64) Line 691	C++	Symbols loaded.
coreclr.dll!Module::Destruct() Line 662	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ClassLoader::FreeModules() Line 1884	C++	Symbols loaded.
coreclr.dll!ClassLoader::~ClassLoader() Line 1946	C++	Symbols loaded.
coreclr.dll!Assembly::Terminate(int) Line 311	C++	Symbols loaded.
coreclr.dll!Assembly::~Assembly() Line 244	C++	Symbols loaded.
coreclr.dll!Assembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
coreclr.dll!DomainAssembly::~DomainAssembly() Line 91	C++	Symbols loaded.
coreclr.dll!DomainAssembly::`scalar deleting destructor'(unsigned int __flags)	C++	Symbols loaded.
>	coreclr.dll!LoaderAllocator::GCLoaderAllocators(LoaderAllocator * pOriginalLoaderAllocator) Line 570	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 702	C++	Symbols loaded.
coreclr.dll!LoaderAllocator_Destroy(QCall::LoaderAllocatorHandle pLoaderAllocator) Line 718	C++	Symbols loaded.
System.Private.CoreLib.dll!00007ffa9c4308f9()	Unknown	No symbols loaded.
coreclr.dll!FastCallFinalizeWorker() Line 26	Unknown	Symbols loaded.
coreclr.dll!MethodTable::CallFinalizer(Object * obj) Line 4908	C++	Symbols loaded.
[Inline Frame] coreclr.dll!CallFinalizer(Object *) Line 75	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizeAllObjects() Line 110	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadWorker(void * args) Line 354	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_DispatchInner(ManagedThreadCallState *) Line 7222	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchMiddle(ManagedThreadCallState * pCallState) Line 7266	C++	Symbols loaded.
coreclr.dll!ManagedThreadBase_DispatchOuter(ManagedThreadCallState * pCallState) Line 7425	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase_NoADTransition(void(*)(void *)) Line 7494	C++	Symbols loaded.
[Inline Frame] coreclr.dll!ManagedThreadBase::FinalizerBase(void(*)(void *)) Line 7513	C++	Symbols loaded.
coreclr.dll!FinalizerThread::FinalizerThreadStart(void * args) Line 403	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

Thread exit with threadlocal cleanup
>	coreclr.dll!LoaderAllocator::SetHandleValue(unsigned __int64 handle, Object *) Line 992	C++	Symbols loaded.
coreclr.dll!LoaderAllocator::FreeHandle(unsigned __int64 handle) Line 884	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTLM(unsigned __int64 i, int isThreadShuttingdown) Line 59	C++	Symbols loaded.
coreclr.dll!ThreadLocalBlock::FreeTable() Line 93	C++	Symbols loaded.
[Inline Frame] coreclr.dll!Thread::DeleteThreadStaticData() Line 7704	C++	Symbols loaded.
coreclr.dll!Thread::OnThreadTerminate(int holdingLock) Line 2956	C++	Symbols loaded.
coreclr.dll!DestroyThread(Thread * th) Line 924	C++	Symbols loaded.
coreclr.dll!ThreadNative::KickOffThread(void * pass) Line 239	C++	Symbols loaded.
kernel32.dll!BaseThreadInitThunk()	Unknown	Symbols loaded.
ntdll.dll!RtlUserThreadStart()	Unknown	Symbols loaded.

with an exception which is thrown with the following details:
Exception thrown: read access violation.
**loaderAllocator** was nullptr.

devenv_iJFpiWBvYe
loaderAllocator value from the LOADERALLOCATORREF loaderAllocator = (LOADERALLOCATORREF)ObjectFromHandle(m_hLoaderAllocatorObjectHandle); call is NULL which makes sense, because finalizer thread just disposed data for some of the same LoaderAllocator assemblies.
Note: enabling COR_PRF_MONITOR_MODULE_LOADS CLR profiler flag increases chances for the race condition as it slows down a bit complete loader destruction.
Changes:
I've looked at the following options as a solution to the problem:
  • Null check for loaderAllocator
  • Wait for GC/Finalizers done before killing thread
  • Skip cleaning up thread locals for unloaded loaders
Based on the discussion the acceptable solution would be to:
  • use coop mode to ensure the loader is not collected while we delete thread local handles (we already do it when setting a handle to NULL, so we elevate the scope with a minimal performance consequences)
  • if loader was already collected we do not need to reset handles as they are going to be deallocated anyway further down the loader destruction
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/azp run runtime-coreclr outerloop
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LGTM. Thank you!
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/backport to release/8.0-staging
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Started backporting to release/8.0-staging: https://github.com/dotnet/runtime/actions/runs/9293876461
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@jkotas backporting to release/8.0-staging failed, the patch most likely resulted in conflicts:
$ git am --3way --ignore-whitespace --keep-non-patch changes.patch
Applying: Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocatorsUsing index info to reconstruct a base tree...M	src/coreclr/vm/threadstatics.cppFalling back to patching base and 3-way merge...Auto-merging src/coreclr/vm/threadstatics.cppCONFLICT (content): Merge conflict in src/coreclr/vm/threadstatics.cpperror: Failed to merge in the changes.hint: Use 'git am --show-current-patch=diff' to see the failed patchhint: When you have resolved this problem, run "git am --continue".hint: If you prefer to skip this patch, run "git am --skip" instead.hint: To restore the original branch and stop patching, run "git am --abort".hint: Disable this message with "git config advice.mergeConflict false"Patch failed at 0001 Ensure LoaderAllocator can't be collected while we clean handles on collectible LoaderAllocators
Error: The process '/usr/bin/git' failed with exit code 128
Please backport manually!
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@jkotas an error occurred while backporting to release/8.0-staging, please check the run log for details!
Error: git am failed, most likely due to a merge conflict.
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@alexey-zakharov If you would like to see this backported to .NET 8, could you please submit a PR against release/8.0-staging branch with the merge conflicts resolved?
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@jkotas I've created a backport PR - #102872

thanks for taking the fix in!
@alexey-zakharov
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@alexey-zakharov@Ruihan-Yin
Ensure LoaderAllocator can't be collected while we clean handles on …
44a2f94
…collectible LoaderAllocators (dotnet#102797)
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