[release/6.0] Fix memory leak at AssemblyLoadContext unload #69334
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I have found there was a small memory leak when unloading AssemblyLoadContext. A customer had a quite extreme testing case that ran millions of iterations of creating an AssemblyLoadContext, loading some assemblies into it and then unloading it. After 80 million iterations on their machine with 8GB memory, the testing app was getting out of memory. Using PerfView, I was able to locate the source of the leak. It was a missing destruction of the Module::m_pJitInlinerTrackingMap.
jeffschwMSFT
approved these changes
May 16, 2022
jkotas
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May 16, 2022
jeffschwMSFT
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@carlossanlop this one is approved and ready to merge when the branch is ready. |
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Backport of #69263 to release/6.0
/cc @janvorli
Customer Impact
Without this fix, an application that creates and unloads collectible AssemblyLoadContext very often gets memory consumption growing indefinitely. So after many iterations, they may get out of memory exception. A customer has experienced this in a stress testing application they have created for their plugin system. The fix in 6.0 is very important for them.
Testing
CoreCLR tests, libraries tests, customer's repro application.
The customer has also tested a patched version of coreclr.dll on their systems and verified it fixes the issues they were seeing.
Risk
Low, it affects only collectible AssemblyLoadContext and the deletion of the data structure was clearly missing.