Parallel compilation may be causing go module races

[tylerphelan]

We've observed non-deterministic behavior when running ginkgo:

for i in `seq 1 20`; do rm -rf /root/go/pkg; ginkgo -r -skipPackage=integration,brats; done

Produces a roughly 50% failure to compile with varying compilation errors.

for i in `seq 1 20`; do rm -rf /root/go/pkg; ginkgo -r -skipPackage=integration,brats -compilers=1; done

Succeeds 100% of the time.

Forcing module download before running tests, for example with go mod download, will also produce 100% success rate.

Our theory is that parallel compilation, and thus parallel module fetching, really confuses go, leading to races in module resolution/solving/whatever you call it.

@Zanadar

[onsi]

I think this is surfacing a bug in go mod download. Seems like go should be able to handle multiple downloads in parallel. I'd suggest y'all open an issue there.

For now the -compilers=1 flag workaround will have to do :/

[tylerphelan]

Looks like the issue is golang/go#26794

[tylerphelan]

Will close for now.