Use static CoreClrAssemblyLoader in the SdkResolverLoader #6864
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We want to use static for CoreClrAssemblyLoader so each unique SDK resolver assembly is loaded into memory and JITted only once.
rainersigwald
approved these changes
Sep 17, 2021
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I've validated that the initial bug hits even in dotnet build scenarios -- we were accidentally loading SDK resolvers approximately one bajillion times more than we needed to.
This looks like a great fix. Thanks @marcin-krystianc!
Forgind
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Thanks, @rainersigwald and @Forgind for jumping on it. |
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Fixes #6842 (comment)
Context
We use static for the
CoreClrAssemblyLoaderfield so each unique SDK resolver assembly is loaded into memory and JITted only once. All subsequent load requests will return assembly from the assembly loader's cache instead of loading it again from disk. This change increases the performance of SDK resolution and at the same time avoids leaking memory due to loading the same SDK resolver assembly multiple times and never unloading it.Changes Made
The
CoreClrAssemblyLoaderfield in theSdkResolverLoaderclass was changed from non-static to static member. The same instance ofCoreClrAssemblyLoaderwill be used by all instances ofSdkResolverLoader. It is consistent now with other uses ofCoreClrAssemblyLoaderin msbuild.Testing
Tested manually using repro from #5037 (comment)
Notes
Alternative approach would be to use collectible
CoreClrAssemblyLoader/AssemblyLoadContext- that would fix the leak as well but it would be less performant as it wouldn't benefit from re-using already loaded and JITed assemblies.