Race condition in "cabal run"

[chreekat]

Context:

I am working on a project that has dozens of packages and ~10 executables. I have created a process-compose.yml that allows me to run the executables in parallel. Each executable is run via cabal run the-executable for simplicity.

Problem:

If the executables need to be rebuilt, or more precisely, a dependency within the project need to be rebuilt, I regularly see errors that look like race conditions caused by a lack of locking. One such error looked like:

ghc-pkg-9.6.6: cannot create: /path/to/project/dist-newstyle/build/x86_64-linux/ghc-9.6.6/THE-DEPENDENCY-0.2.0.0/noopt/package.conf.inplace already exists

Obviously this particular error is coming from ghc-pkg, so you could argue it's a ghc-pkg bug. But I assume cabal is responsible for the invocations of ghc-pkg in the first place. As the coordinator, cabal should probably recognize when another instance is already building a given package, and wait.

Cabal version: 3.12.1.0