[Bug libgomp/88707] Random failures of libgomp.c++/task-reduction-(8|10|11|13).C

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88707

Rainer Orth <ro at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|x86_64-apple-darwin18       |x86_64-apple-darwin18,
                   |                            |*-*-solaris2.11,
                   |                            |i586-unknown-freebsd11.2
                 CC|                            |ro at gcc dot gnu.org
               Host|x86_64-apple-darwin18       |
            Summary|Random failures of          |Random failures of
                   |libgomp.c++/task-reduction- |libgomp.c++/task-reduction-
                   |(8|10).C on                 |(8|10|11|13).C
                   |x86_64-apple-darwin18       |
              Build|x86_64-apple-darwin18       |

--- Comment #3 from Rainer Orth <ro at gcc dot gnu.org> ---
I'm seeing exactly the same on Solaris (both sparc and x86, 32 and 64-bit), and
there are also FreeBSD reports.

On Solaris, the affected tests

FAIL: libgomp.c++/task-reduction-10.C execution test
FAIL: libgomp.c++/task-reduction-11.C execution test
FAIL: libgomp.c++/task-reduction-13.C execution test
FAIL: libgomp.c++/task-reduction-8.C execution test

usually complete within 10 ms, but every once in a while they hang
indefinitely,
running into the DejaGnu timeout.  This even happens on a completely unloaded
machine, running only a single testcase manually.  Things seem to get worse
with OMP_NUM_THREADS=8 set.

Seems like a deadlock to me:

Thread 16 (Thread 8        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd698) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 15 (Thread 7        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd654) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 14 (Thread 6        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd610) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 13 (Thread 5        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd5cc) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 12 (Thread 4        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd588) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 11 (Thread 3        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd544) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 9 (LWP    8        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd698) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 8 (LWP    7        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd654) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 7 (LWP    6        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd610) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 6 (LWP    5        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd5cc) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 5 (LWP    4        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd588) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 4 (LWP    3        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/l
ibgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe40f437 in gomp_barrier_wait_last (bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:116
#9  gomp_thread_start (xdata=0xfeffd544) at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:111
#10 0xfe29a779 in _thrp_setup () from /lib/libc.so.1
#11 0xfe29aa60 in ?? () from /lib/libc.so.1
#12 0x00000000 in ?? ()

Thread 2 (Thread 1        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe410967 in gomp_team_end () at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:965
#9  0xfe406c98 in GOMP_parallel_reductions (fn=0x80513f0 <void bar<int, long
long>() [clone ._omp_fn.1]>, data=0xfeffd7f0, num_threads=8, flags=0) at
/vol/gcc/src/hg/trunk/local/libgomp/parallel.c:186
#10 0x0805154f in void bar<int, long long>() [clone ._omp_fn.0] ()
#11 0xfe406c30 in GOMP_parallel (fn=0x80514d0 <void bar<int, long long>()
[clone ._omp_fn.0]>, data=0xfeffd8c8, num_threads=1, flags=0) at
/vol/gcc/src/hg/trunk/local/libgomp/parallel.c:171
#12 0x08051719 in void bar<int, long long>() ()
#13 0x0805175b in main ()

Thread 1 (LWP    1        ):
#0  0xfe29aab9 in __lwp_park () from /lib/libc.so.1
#1  0xfe28c1ff in sema_wait_impl () from /lib/libc.so.1
#2  0xfe28c3c3 in sema_wait () from /lib/libc.so.1
#3  0xfe27e967 in sem_wait () from /lib/libc.so.1
#4  0xfe4115bc in gomp_sem_wait (sem=0x8067924) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/sem.c:121
#5  0xfe41174c in gomp_barrier_wait_end (state=8, bar=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:92
#6  gomp_barrier_wait_end (bar=0x806790c, state=8) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.c:73
#7  0xfe4117c3 in gomp_barrier_wait (barrier=0x806790c) at
/vol/gcc/src/hg/trunk/local/libgomp/config/posix/bar.h:85
#8  0xfe410967 in gomp_team_end () at
/vol/gcc/src/hg/trunk/local/libgomp/team.c:965
#9  0xfe406c98 in GOMP_parallel_reductions (fn=0x80513f0 <void bar<int, long
long>() [clone ._omp_fn.1]>, data=0xfeffd7f0, num_threads=8, flags=0) at
/vol/gcc/src/hg/trunk/local/libgomp/parallel.c:186
#10 0x0805154f in void bar<int, long long>() [clone ._omp_fn.0] ()
#11 0xfe406c30 in GOMP_parallel (fn=0x80514d0 <void bar<int, long long>()
[clone ._omp_fn.0]>, data=0xfeffd8c8, num_threads=1, flags=0) at
/vol/gcc/src/hg/trunk/local/libgomp/parallel.c:171
#12 0x08051719 in void bar<int, long long>() ()
#13 0x0805175b in main ()