data race with example_hyper about rust-prometheus HOT 6 CLOSED

/cc @overvenus

from rust-prometheus.

Be aware that there could be false positives. See https://users.rust-lang.org/t/howto-sanitize-your-rust-code/9378/22. And https://github.com/japaric/rust-san#better-backtraces could be useful too.

from rust-prometheus.

Thanks @BrunoQC

We will fix it later, or could you send us a PR to fix it?

from rust-prometheus.

Hi @BrunoQC ,

Sorry for the super late reply.

The SUMMARY indicates that the data race happens in crate lazy-static.

        unsafe {
            let r = &mut self.0;
            self.1.call_once(|| {
                *r = Box::into_raw(Box::new(f())); // write
            });

            &*self.0 // read
        }

@parched said that

This will be a false positive because drop_slow uses a fence, and tsan doesn't work with fences.

rust-lang/rust#39608 (comment)

I am not so familiar with atomic and fence, not sure if this is false positive. I will investigate further. 😄

from rust-prometheus.

Looks like is probably call_once. I had a look at the source though and couldn't see anything obvious, it certainly doesn't use fences that I could see. It would be good to run it with better backtraces (link earlier) to see exactly where it is happening.

from rust-prometheus.

Looks to be a false positive. Closing.

from rust-prometheus.