x/tools/gopls: race in updateAnalyzers

[stamblerre]

Seen on CL 215743, which was not related.

This is specific to the tests in golang.org/x/tools/gopls/test, because they pass an options modification function (with the signature func(*source.Options)) that updates the analyzers map. All of the command tests use this type of function, but only the gopls/test ones modify a map. A possible solution would be to have a mutex on the options before modifying them.

[stamblerre]

I'm actually not sure how to fix this effectively since all of the fields in the options are exported.
@heschik, @ianthehat: Do you have any suggestions here?

[heschik]

I set GORACE=history_size=7 and had no luck getting the other side of the race.

[stamblerre]

After offline discussion with @ianthehat, @heschik will look into the possibility of setting GORACE=history_size to a much higher value so that we can see where the previous write is.

[zikaeroh]

#36872's logs actually show the other side of the race:

Previous read at 0x00c0001ce168 by goroutine 911:
  golang.org/x/tools/internal/lsp/source.analyses()
      /tmp/workdir/gopath/src/golang.org/x/tools/internal/lsp/source/diagnostics.go:183 +0x174
  golang.org/x/tools/internal/lsp/source.Diagnostics()
      /tmp/workdir/gopath/src/golang.org/x/tools/internal/lsp/source/diagnostics.go:91 +0x739
  golang.org/x/tools/internal/lsp.(*Server).diagnose.func1.1()
      /tmp/workdir/gopath/src/golang.org/x/tools/internal/lsp/diagnostics.go:58 +0x1cb

[gopherbot]

Change https://golang.org/cl/216844 mentions this issue: internal/lsp/source: check cancellation before analysis