Re: [Qemu-devel] Remaining CI failures

[Emilio G. Cota]

On Fri, Jan 11, 2019 at 19:10:07 +0000, Alex Bennée wrote:
> So trying to narrow down the remaining failures in the CI system. There
> is one with a patch in flight (use g_usleep instead of sleep) but there
> remains two failure modes, both erratic.
> 
> tests/qht-par:
> 
> I can trigger this on my dev machine with a gprof enabled build:
> 
>   # QEMU configure log Fri Jan 11 14:10:45 GMT 2019
>   # Configured with: './configure' '--disable-tools' '--disable-docs' 
> '--enable-gprof' '--enable-gcov'
> 
> I only seem to be able to trigger it when running via the wrapper in the
> make system:
> 
>   retry.py -n 30 --invert make check-tests/test-qht-par
> 
> Eventually this crashes with:
> 
>   ERROR:tests/test-qht-par.c:20:test_qht: assertion failed (rc == 0): (35584 
> == 0)
> 
> Leaving a core dump for the child:

I can't replicate this on my machine :-(

I suspect this is probably related to the fact that gprof
is not even meant to support multi-threaded programs (like qht-bench).

Given that we've fixed the sleep issue (thanks!) and that there is no use
in running test-qht-par under gprof, I propose to permanently skip
it under gprof, e.g.:

--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -88,7 +88,8 @@ check-unit-y += tests/test-rcu-simpleq$(EXESUF)
 check-unit-y += tests/test-rcu-tailq$(EXESUF)
 check-unit-y += tests/test-qdist$(EXESUF)
 check-unit-y += tests/test-qht$(EXESUF)
-# FIXME: {test-qht-par + gprof} often break on Travis CI
+# test-qht-par invokes qht-bench, which is multi-threaded.
+# gprof doesn't support multi-threaded programs, so skip this test under gprof.
 check-unit-$(call lnot,$(CONFIG_GPROF)) += tests/test-qht-par$(EXESUF)
 check-unit-y += tests/test-bitops$(EXESUF)
 check-unit-y += tests/test-bitcnt$(EXESUF)

If you agree, I can submit a proper patch with the above.

Thanks,

                Emilio