* [PATCH] gdb/testsuite: fix race condition in gdb.python/py-thread-exited.exp
@ 2023-08-14 20:58 Andrew Burgess
2023-08-15 13:36 ` Tom Tromey
0 siblings, 1 reply; 3+ messages in thread
From: Andrew Burgess @ 2023-08-14 20:58 UTC (permalink / raw)
To: gdb-patches; +Cc: Tom Tromey, Simon Farre, Andrew Burgess
I ran into a test failure on gdb.python/py-thread-exited.c. The test
creates two threads and then catches the thread exits in Python. The
test expects the threads to exit in a specific order.
As the test is currently written, it is _likely_, but not guaranteed,
that the threads will exit in the same order they are created, which
is what the test expects.
When running on a loaded system I ran into a case where the threads
exited in the reverse creation order, which caused the test to fail.
I could fix this by having the .exp file not care about the thread
order, or by changing the C file to force the order. I chose the
later, and added a pthread_barrier_t to ensure the threads exit in the
correct order.
There should be no change in what is tested after this commit.
---
gdb/testsuite/gdb.python/py-thread-exited.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/gdb/testsuite/gdb.python/py-thread-exited.c b/gdb/testsuite/gdb.python/py-thread-exited.c
index d62133ba59e..4df6b587935 100644
--- a/gdb/testsuite/gdb.python/py-thread-exited.c
+++ b/gdb/testsuite/gdb.python/py-thread-exited.c
@@ -24,14 +24,25 @@ pthread_t thread3_id;
void* do_thread (void* d)
{
+ if (d != NULL)
+ {
+ pthread_barrier_t *barrier = (pthread_barrier_t *) d;
+ pthread_barrier_wait (barrier);
+ }
+
return NULL; /* In thread */
}
int main (void)
{
+ /* We want the threads to exit in a known order. Use a barrier to ensure
+ the second thread doesn't exit until the first has been joined. */
+ pthread_barrier_t barrier;
+ pthread_barrier_init (&barrier, NULL, 2);
pthread_create (&thread2_id, NULL, do_thread, NULL);
- pthread_create (&thread3_id, NULL, do_thread, NULL);
+ pthread_create (&thread3_id, NULL, do_thread, &barrier);
pthread_join (thread2_id, NULL);
+ pthread_barrier_wait (&barrier);
pthread_join (thread3_id, NULL);
return 12; /* Done */
}
base-commit: 86dfe011797b3e442622d427e9abd1e0f70f3a62
--
2.25.4
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] gdb/testsuite: fix race condition in gdb.python/py-thread-exited.exp
2023-08-14 20:58 [PATCH] gdb/testsuite: fix race condition in gdb.python/py-thread-exited.exp Andrew Burgess
@ 2023-08-15 13:36 ` Tom Tromey
2023-08-16 14:04 ` Andrew Burgess
0 siblings, 1 reply; 3+ messages in thread
From: Tom Tromey @ 2023-08-15 13:36 UTC (permalink / raw)
To: Andrew Burgess; +Cc: gdb-patches, Tom Tromey, Simon Farre
>>>>> "Andrew" == Andrew Burgess <aburgess@redhat.com> writes:
Andrew> I could fix this by having the .exp file not care about the thread
Andrew> order, or by changing the C file to force the order. I chose the
Andrew> later, and added a pthread_barrier_t to ensure the threads exit in the
Andrew> correct order.
Looks good to me, thanks.
Tom
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] gdb/testsuite: fix race condition in gdb.python/py-thread-exited.exp
2023-08-15 13:36 ` Tom Tromey
@ 2023-08-16 14:04 ` Andrew Burgess
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Burgess @ 2023-08-16 14:04 UTC (permalink / raw)
To: Tom Tromey; +Cc: gdb-patches, Tom Tromey, Simon Farre
Tom Tromey <tromey@adacore.com> writes:
>>>>>> "Andrew" == Andrew Burgess <aburgess@redhat.com> writes:
>
> Andrew> I could fix this by having the .exp file not care about the thread
> Andrew> order, or by changing the C file to force the order. I chose the
> Andrew> later, and added a pthread_barrier_t to ensure the threads exit in the
> Andrew> correct order.
>
> Looks good to me, thanks.
Pushed.
Thanks,
Andrew
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-08-14 20:58 [PATCH] gdb/testsuite: fix race condition in gdb.python/py-thread-exited.exp Andrew Burgess
2023-08-15 13:36 ` Tom Tromey
2023-08-16 14:04 ` Andrew Burgess
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