[llvm-dev] [lit] check-all hanging

[Dmitry Vyukov via llvm-dev]

On Fri, Jan 4, 2019 at 5:55 PM David Greene <dag at cray.com> wrote:
>
> Dmitry Vyukov <dvyukov at google.com> writes:
>
> > Are there any special repro instructions? I am running all tsan tests
> > periodically on linux and none of them flakes.
>
> I don't think I'm doing anything especially interesting.  I wonder if
> lit parallelism has anything to do with it.  I tend to run quite wide
> (32 or more).
>
> I'm on SLES 12.2, kernel 4.4.21-69-default, x86_64 in case it matters.
> I see this test hang pretty frequently.

Hi David,

The test is specifically a regression test for a deadlock:

// Make sure TSan doesn't deadlock on a file stream lock at program shutdown.
// See https://github.com/google/sanitizers/issues/454

So I wonder if it's not completely fixed.
I am sure it does not reproduce on my machine:

$ clang++ getline_nohang.cc -fsanitize=thread -O1 -g
$ stress ./a.out
192 runs so far, 0 failures
...
17137 runs so far, 0 failures
17377 runs so far, 0 failures

Could you please attach to the hanged process with gdb and do
backtrace of all threads?