sync.Pool behaviour under -race

[Matt Joiner]

I have some tests that check the behaviour of sync.Pool. When running the tests with -race, those tests fail. Specifically, putting an item into a sync.Pool does not mean it will be available immediately after. While this might not be a guarantee of sync.Pool anyway, what causes this differing behaviour here? How can I determine if the race detector is running, and skip this test in that instance?

[Roberto Zanotto]

from: https://golang.org/src/sync/pool.go

// Under race detector the Pool degenerates into no-op.
// It's conforming, simple and does not introduce excessive
// happens-before edges between unrelated goroutines.

Basically you get a new item (or nil) each time you ask for one and putting back things into the pool does nothing.

When you have doubts, read the code :)

[Matt Joiner]

Ah, thanks! How about the other part, detecting if the race detector is running? I'd assume something like testing.Race(), in line with testing.Verbose().

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[Roberto Zanotto]

You should be able to check if the race detector is enabled with the "race" build tag
https://golang.org/src/internal/race/race.go

On Thursday, May 12, 2016 at 4:38:31 AM UTC+2, Matt Joiner wrote:

[Caleb Spare]

You should instead fix your tests not to require any behavior that isn't guaranteed by the interface you're using.

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[Matt Joiner]

Thanks for that, it worked well.

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[Roberto Zanotto]

Glad I could help.

Consider also Caleb's advice, it's not your responsibility to test that Pool does its job.