tye run --watch has locking issues with project used multiple times, and replicas

[JamesNK]

Example tye.yaml:

name: microservice
services:
- name: frontend
  project: frontend/frontend.csproj
- name: backend-1
  project: backend/backend.csproj
- name: backend-2
  project: backend/backend.csproj

Starting projects with tye run --watch succeeds, but when a file changes in the backend project the build fails with locking issues:

[11:09:50 INF] Building projects failed with exit code 1:
  Determining projects to restore...
  All projects are up-to-date for restore.
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018: The "CreateAppHost" task failed unexpectedly. [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018: System.AggregateException: One or more errors occurred. (800703EE) (The process cannot access the file 'C:\Development\Temp\microservice\backend\obj\Debug\netcoreapp3.1\backend.exe' because it is being used by another process.) [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:  ---> Microsoft.NET.HostModel.HResultException: 800703EE [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at Microsoft.NET.HostModel.ResourceUpdater.ThrowExceptionForLastWin32Error() [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.HostWriter.<>c__DisplayClass2_0.<CreateAppHost>g__UpdateResources|1() [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at Microsoft.NET.HostModel.RetryUtil.RetryOnWin32Error(Action func) [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.HostWriter.CreateAppHost(String appHostSourceFilePath, String appHostDestinationFilePath, String appBinaryFilePath, Boolean windowsGraphicalUserInterface, String assemblyToCopyResorcesFrom) [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    --- End of inner exception stack trace --- [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.HostWriter.CreateAppHost(String appHostSourceFilePath, String appHostDestinationFilePath, String appBinaryFilePath, Boolean windowsGraphicalUserInterface, String assemblyToCopyResorcesFrom) [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at Microsoft.NET.Build.Tasks.CreateAppHost.ExecuteCore() [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at Microsoft.NET.Build.Tasks.TaskBase.Execute() [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute() [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask) [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:  ---> (Inner Exception #1) System.IO.IOException: The process cannot access the file 'C:\Development\Temp\microservice\backend\obj\Debug\netcoreapp3.1\backend.exe' because it is being used by another process. [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at System.IO.FileSystem.DeleteFile(String fullPath) [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at System.IO.File.Delete(String path) [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:    at Microsoft.NET.HostModel.AppHost.HostWriter.CreateAppHost(String appHostSourceFilePath, String appHostDestinationFilePath, String appBinaryFilePath, Boolean windowsGraphicalUserInterface, String assemblyToCopyResorcesFrom)<--- [C:\Development\Temp\microservice\backend\backend.csproj]
C:\Program Files\dotnet\sdk\3.1.300\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets(424,5): error MSB4018:  [C:\Development\Temp\microservice\backend\backend.csproj]

Build FAILED.

This is also a problem when there is a single project configured with multiple replicas.

[jkotalik]

I looked into this briefly as well. I think an approach could be to create a mapping from replica or service name to the csproj file and have a corresponding lock with it. Once watch triggers, whoever acquires the lock first runs dotnet build, while the other project waits on the lock. You'd need some sort of dirty/built flag as well to make sure you don't trigger multiple builds for each change.