Support EventSource/event pipe in shared libraries

[MichalStrehovsky]

When EventSourceSupport MSBuild property is set to true, the build currently errors out. It is possible to bypass this by setting _SuppressNativeLibEventSourceError property to true but there are known issues. It is not recommended to ship native libraries like this unless one can make sure no other native library (or a CoreCLR instance) with EventSourceSupport gets loaded into the process. Users might consider shipping two versions of their native library DLL and only use the one with EventSourceSupport enabled when troubleshooting a specific issue.

This is a tracking uber issue that groups the known existing problems:

• Define and implement behavior of NativeAOT EventPipe IPC if there's already another runtime in the process #88087
• (Windows only) EventPipe hangs with a shared NativeAOT library #89346

Our guidance for EventSource/EventPipe with native AOT shared libraries is as follows,

• Only use the EventSourceSupport enabled when troubleshooting a specific issue related to shared libraries.
• Any native AOT console with EventSourceSupport enabled will always win even if the process has other native AOT shared libraries with EventSourceSupport enabled.
• If there are multiple native AOT shared libraries present in a single process, then the first shared library that gets loaded will win to emit traces. Traces from other libraries will not be seen.
• [Windows] When collecting tracing in a shared library, collection should stop earlier in the application (only collect for a specific time period or use the ctrl-C option with a tool like dotnet-trace when the interesting traces are collected). Specifically, in windows, the image unload event for a shared library (or at process exit), will not make a call to shut down the EventPipe in an orderly manner, causing a corrupted trace file.

Given these challenges, it's probably best to keep the current warnings we have for shared library around EventSource support.

[ghost]

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Issue Details

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When EventSourceSupport MSBuild property is set to true, the build currently errors out. It is possible to bypass this by setting _SuppressNativeLibEventSourceError property to true but there are known issues. It is not recommended to ship native libraries like this unless one can make sure no other native library (or a CoreCLR instance) with EventSourceSupport gets loaded into the process. Users might consider shipping two versions of their native library DLL and only use the one with EventSourceSupport enabled when troubleshooting a specific issue.

This is a tracking uber issue that groups the known existing problems:

• Define and implement behavior of NativeAOT EventPipe IPC if there's already another runtime in the process #88087
• (Windows only) EventPipe hangs with a shared NativeAOT library #89346

Author:	MichalStrehovsky
Assignees:	-
Labels:	area-NativeAOT-coreclr
Milestone:	Future