[go-nuts] Why does the race detector set atexit_sleep_ms=1000 by default?

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;

--

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.