Determinism changes. #255
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Determinism changes. #255
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1. The timer workaround is no longer needed since EventPipe file polling was removed in dotnet/coreclr#24225 2. dotnet/runtime#467 introduced a change that causes pmi non determinism. System.Threading.Thread.s_isProcessorNumberReallyFast can have different values on two invocations of the process on the same machine. (https://github.com/dotnet/runtime/blob/aedf8f52006619ef5d4eca65d79f42cc4b7bc402/src/coreclr/src/System.Private.CoreLib/src/System/Threading/Thread.CoreCLR.cs#L502) That causes non-determinism in generated code in methods' inlining System.Threading.Thread.GetCurrentProcessorId() (https://github.com/dotnet/runtime/blob/aedf8f52006619ef5d4eca65d79f42cc4b7bc402/src/coreclr/src/System.Private.CoreLib/src/System/Threading/Thread.CoreCLR.cs#L492-L498) The workaround is to set the value of System.Threading.Thread.s_isProcessorNumberReallyFast to true via reflection.
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@AndyAyersMS @sandreenko @dotnet/jit-contrib PTAL |
sandreenko
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BruceForstall
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erozenfeld
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I added a workaround for disassembly non-determinism in dotnet#255. See dotnet#255 for details of what causes the non-determinism. It turns it relied on a reflection hole that allowed init-only static fields to be modified after static constructor has been called. That hole was fixed in dotnet/runtime#37849 so the workaround is no longer valid and causes an exception from pmi. I don't see a way to work around the non-determinism without changing framework code so for now I'm just reverting the workaround. Unfortunately, that means that we can get non-deterministic disassembly for any method that inlines System.Threading.Thread.GetCurrentProcessorId. Fixes dotnet#271.
erozenfeld
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Jun 19, 2020
I added a workaround for disassembly non-determinism in #255. See #255 for details of what causes the non-determinism. It turns it relied on a reflection hole that allowed init-only static fields to be modified after static constructor has been called. That hole was fixed in dotnet/runtime#37849 so the workaround is no longer valid and causes an exception from pmi. I don't see a way to work around the non-determinism without changing framework code so for now I'm just reverting the workaround. Unfortunately, that means that we can get non-deterministic disassembly for any method that inlines System.Threading.Thread.GetCurrentProcessorId. Fixes #271.
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The timer workaround is no longer needed since EventPipe file polling
was removed in Removing EventPipe file polling (EventPipeController+Timer) coreclr#24225
Adjusting
GetCurrentProcessorIdcaching to different environments. runtime#467 introduced a change thatcauses pmi non-determinism.
System.Threading.Thread.s_isProcessorNumberReallyFast can have different
values on two invocations of the process on the same machine.
(https://github.com/dotnet/runtime/blob/aedf8f52006619ef5d4eca65d79f42cc4b7bc402/src/coreclr/src/System.Private.CoreLib/src/System/Threading/Thread.CoreCLR.cs#L502)
That causes non-determinism in generated code in methods
inlining System.Threading.Thread.GetCurrentProcessorId()
(https://github.com/dotnet/runtime/blob/aedf8f52006619ef5d4eca65d79f42cc4b7bc402/src/coreclr/src/System.Private.CoreLib/src/System/Threading/Thread.CoreCLR.cs#L492-L498)
The workaround is to set the value of
System.Threading.Thread.s_isProcessorNumberReallyFast to true via
reflection.