Non-deterministic concurrency issues in solutions with multiple projects

[natemcmaster]

I'm seeing concurrency issues that occurs when calling dotnet build SomeProject.sln. The errors I see do not occur on every build, nor does there seem to be any pattern to when they occur. The errors can occur on first builds after a fresh clone as much as they will occur on second and third builds.

The only thing that seems to be consistent is that it occurs in projects with multiple project references.

The project: DotNetTools.zip

Versions:
dotnet-cli 1.0.0-preview4-004215
Windows 10

Detailed log: msbuild.log.txt

The errors:

CSC : error CS2012: Cannot open 'C:\dev\Universe\DotNetTools\test\Microsoft.DotNet.Watcher.Tools.Tests\obj\Debug\netcoreapp1.0\Microsoft.DotNet.Watcher.Tools.Tests.dll' for writing -- 'The process cannot access the file 'C:\dev\Universe\DotNetTools\test\Microsoft.DotNet.Watcher.Tools.Tests\obj\Debug\netcoreapp1.0\Microsoft.DotNet.Watcher.Tools.Tests.dll' because it is being used by another process.' [C:\dev\Universe\DotNetTools\test\Microsoft.DotNet.Watcher.Tools.Tests\Microsoft.DotNet.Watcher.Tools.Tests.csproj]

C:\dev\Universe\DotNetTools.dotnet\sdk\1.0.0-preview4-004215\Sdks\Microsoft.NET.Sdk\build\Microsoft.NET.Sdk.targets(119,5): error MSB4018: The "GenerateRuntimeConfigurationFiles" task failed unexpectedly.\r [C:\dev\Universe\DotNetTools\test\Microsoft.DotNet.Watcher.Tools.Tests\Microsoft.DotNet.Watcher.Tools.Tests.csproj]
C:\dev\Universe\DotNetTools.dotnet\sdk\1.0.0-preview4-004215\Sdks\Microsoft.NET.Sdk\build\Microsoft.NET.Sdk.targets(119,5): error MSB4018: System.IO.IOException: The process cannot access the file 'C:\dev\Universe\DotNetTools\test\Microsoft.DotNet.Watcher.Tools.Tests\bin\Debug\netcoreapp1.0\Microsoft.DotNet.Watcher.Tools.Tests.runtimeconfig.json' because it is being used by another process.\r [C:\dev\Universe\DotNetTools\test\Microsoft.DotNet.Watcher.Tools.Tests\Microsoft.DotNet.Watcher.Tools.Tests.csproj]

[fearthecowboy]

We're seeing this too-a lot.

It looks like it's rebuilding the same dependent project if multiple projects depend on it.

Ie, if A depends on B , C , D, E, F and C and D and E depend on G ... we see conflicts.

[Eilon]

Hi folks, I was talking to @natemcmaster today and he tried a newer build and this issue didn't repro.

Is this issue officially resolved? Or maybe we just got "lucky" in our build and it happened to succeed?

[srivatsn]

No we haven't been able to figure out the root cause. Unless something changed in msbuild - @AndyGerlicher @rainersigwald, you may have just gotten lucky.