Apparent compiler deadlock when compiling multiple separate projects in parallel #9187
Description
This is happening in Zig.Sdk, so this is easiest to reproduce if you're willing to install the .NET SDK.
Basically, do this:
$ git clone git@github.com:alexrp/zig-msbuild-sdk.git
$ dotnet build src/sdk
$ dotnet build src/samples -v:n -p:BuildInParallel=trueThat last dotnet build invocation will sometimes hang. So far, it always seems to happen either when building two executables or two dynamic libraries at the same time; building an executable and a dynamic library at the same time appears to be fine. But this might be a red herring.
Attempting to cancel the build...
5>C:\Users\alex\source\repos\zig-msbuild-sdk\pkg\cache\zig.sdk\1.0.1-dev.g5da2354e66\build\Zig.Sdk.Build.targets(7,9): warning MSB5021: Terminating the task executable "zig" and its child processes because the build was canceled. [C:\Users\alex\source\repos\zig-msbuild-sdk\src\samples\clib\clib.cproj]
3>C:\Users\alex\source\repos\zig-msbuild-sdk\pkg\cache\zig.sdk\1.0.1-dev.g5da2354e66\build\Zig.Sdk.Build.targets(7,9): warning MSB5021: Terminating the task executable "zig" and its child processes because the build was canceled. [C:\Users\alex\source\repos\zig-msbuild-sdk\src\samples\cxxlib\cxxlib.cxxproj]
Attempting to cancel the build...
5>C:\Users\alex\source\repos\zig-msbuild-sdk\pkg\cache\zig.sdk\1.0.1-dev.g5da2354e66\build\Zig.Sdk.Build.targets(7,9): warning MSB5021: Terminating the task executable "zig" and its child processes because the build was canceled. [C:\Users\alex\source\repos\zig-msbuild-sdk\src\samples\cxxlib\cxxlib.cxxproj]
7>C:\Users\alex\source\repos\zig-msbuild-sdk\pkg\cache\zig.sdk\1.0.1-dev.g5da2354e66\build\Zig.Sdk.Build.targets(7,9): warning MSB5021: Terminating the task executable "zig" and its child processes because the build was canceled. [C:\Users\alex\source\repos\zig-msbuild-sdk\src\samples\clib\clib.cproj]
Attempting to cancel the build...
2>C:\Users\alex\source\repos\zig-msbuild-sdk\pkg\cache\zig.sdk\1.0.1-dev.g5da2354e66\build\Zig.Sdk.Build.targets(7,9): warning MSB5021: Terminating the task executable "zig" and its child processes because the build was canceled. [C:\Users\alex\source\repos\zig-msbuild-sdk\src\samples\cexe\cexe.cproj]
3>C:\Users\alex\source\repos\zig-msbuild-sdk\pkg\cache\zig.sdk\1.0.1-dev.g5da2354e66\build\Zig.Sdk.Build.targets(7,9): warning MSB5021: Terminating the task executable "zig" and its child processes because the build was canceled. [C:\Users\alex\source\repos\zig-msbuild-sdk\src\samples\cxxexe\cxxexe.cxxproj]
Note: Zig.Sdk normally fetches the Zig compiler (0.8.0) from NuGet but it can be overridden to use a local build by doing dotnet build src/samples -v:n -p:BuildInParallel -p:ZigExePath="path/to/zig". Also, I've seen this happen on all platforms (not just Windows) in CI.