Integrated: JDK-8263871: On sem_destroy() failing we should assert
Thomas Stuefe
stuefe at openjdk.java.net
Sat Mar 20 05:54:43 UTC 2021
On Fri, 19 Mar 2021 14:07:59 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:
> This is rather trivial.
>
> We use anonymous Posix semaphores for some synchronization in hotspot. `sem_destroy()` can fail on some platforms with EBUSY if the semaphore has outstanding waiters. The glibc does not care, will happily wipe the sem_t structure and report success. But other Unices care (eg BSD, AIX, HP-UX) and refuse to close the semaphore, leaving the sem_t structure untouched.
>
> It then happened for us that a new semaphore was created at the exact location of the old, still unclosed semaphore, and the unchanged sem_t structure was fed to sem_init(), which would fail with the same EBUSY error and trigger a guarantee.
>
> One simple thing we should do is to assert success after closing a semaphore, as we do on all other semaphore operations. Granted, we won't see anything on Linux with glibc, but maybe shake loose errors on other platforms.
This pull request has now been integrated.
Changeset: 5b8233ba
Author: Thomas Stuefe <stuefe at openjdk.org>
URL: https://git.openjdk.java.net/jdk/commit/5b8233ba
Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
8263871: On sem_destroy() failing we should assert
Reviewed-by: dholmes
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PR: https://git.openjdk.java.net/jdk/pull/3089
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