Why does the race detector set atexit_sleep_ms=1000 by default?

[Rémy Oudompheng]

Hello,

Race detection enabled binaries all sleep for 1 second before exiting.
Why is it so? I have to set GORACE=atexit_sleep_ms=0 to make it run normally.

Rémy.

[minux]

On Mon, Jan 28, 2013 at 2:20 AM, Rémy Oudompheng <remyoud...@gmail.com> wrote:

Race detection enabled binaries all sleep for 1 second before exiting.
Why is it so? I have to set GORACE=atexit_sleep_ms=0 to make it run normally.

it aims to catch races involving C's atexit().

however, Go doesn't have atexit() so i think we can apply this patch to compiler_rt.

diff --git a/lib/tsan/rtl/tsan_flags.cc b/lib/tsan/rtl/tsan_flags.cc

index 88c4bb6..f0bd238 100644

--- a/lib/tsan/rtl/tsan_flags.cc

+++ b/lib/tsan/rtl/tsan_flags.cc

@@ -50,7 +50,7 @@ void InitializeFlags(Flags *f, const char *env) {

   f->suppressions = "";

   f->exitcode = 66;

   f->log_path = "stderr";

-  f->atexit_sleep_ms = 1000;

+  f->atexit_sleep_ms = kGoMode ? 0 : 1000; // no atexit() for Go

   f->verbosity = 0;

   f->profile_memory = "";

   f->flush_memory_ms = 0;

[Dmitry Vyukov]

Hi,

atexit_sleep_ms had proven to be extremely useful in C++ land to catch races between background threads and destructors of globals/function static objects.

I don't remember any Go atexit races (but I've seen much less Go races than C++ races, though). But the idea that you may have:

func main() {

  ...

  go backgroundProcess(...)

  ...

  ...

  foo.Shutdown()

}

func backgroundProcess(...) {

  for {

    time.Sleep(time.Second)

    foo.DoSomething()

  }
}

Here we have a race between foo.DoSomething() and foo.Shutdown(), but it unlikely will be found w/o atexit_sleep_ms.

Can you describe the context in which you need to set atexit_sleep_ms=0?

The concern is that if we set it to 0, since it only leads to false negatives, nobody will ever turn it on.