The proposed solution here is to make the casing of the path provided to the hashing function for the mutex consistent with something like:
public static string GetUniqueMutexForPath(string Name, string UniquePath) { return String.Format("Global\\{0}_{1}", Name, UniquePath.ToLower().GetHashCode()); }
By adding ToLower to UniquePath.
Run something similar to this from a batch file:
start cmd.exe /k D:\ue4\Engine\Binaries\DotNet\UnrealBuildTool.exe ShaderCompileWorker Win64 Development -NoHotReloadFromIDE -WaitMutex -progress start cmd.exe /k d:\ue4\Engine\Binaries\DotNet\UnrealBuildTool.exe ShaderCompileWorker Win64 Development -NoHotReloadFromIDE -WaitMutex -progress
Note how the case of the drive letter is different. *D:* and *d:*. Any case-sensitive difference of the path will cause this problem, but the correctness of the drive letter can be the most undefined. One of the builds will probably fail with:
ERROR: Unhandled exception: System.Exception: Unable to open log file for writing (D:\ue4\Engine\Programs\UnrealBuildTool\Log.txt) ---> System.IO.IOException: The process cannot access the file 'D:\ue4\Engine\Programs\UnrealBuildTool\Log.txt' because it is being used by another process. at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-105027 in the post.
| 0 |
| Component | UE - Foundation - Cpp Tools - UnrealBuildTool |
|---|---|
| Affects Versions | 4.26 |
| Target Fix | 4.26.1 |
| Created | Jan 5, 2021 |
|---|---|
| Resolved | Jan 6, 2021 |
| Updated | Apr 27, 2021 |