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98c5847727
This change fixes a bug where nsync waiter objects would leak. It'd mean that long-running programs like runitd would run out of file descriptors on NetBSD where waiter objects have ksem file descriptors. On other OSes this bug is mostly harmless since the worst that can happen with a futex is to leak a little bit of ram. The bug was caused because tib_nsync was sneaking back in after the finalization code had cleared it. This change refactors the thread exiting code to handle nsync teardown appropriately and in making this change I found another issue, which is that user code which is buggy, and tries to exit without joining joinable threads which haven't been detached, would result in a deadlock. That doesn't sound so bad, except the main thread is a joinable thread. So this deadlock would be triggered in ways that put libc at fault. So we now auto-join threads and libc will log a warning to --strace when that happens for any thread |
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|---|---|---|
| .. | ||
| mem | ||
| testing | ||
| array.internal.h | ||
| atomic.h | ||
| atomic.internal.h | ||
| BUILD.mk | ||
| common.c | ||
| common.internal.h | ||
| compat.S | ||
| counter.h | ||
| cv.h | ||
| debug.h | ||
| heap.internal.h | ||
| LICENSE.txt | ||
| mu.c | ||
| mu.h | ||
| mu_semaphore.c | ||
| mu_semaphore.h | ||
| mu_semaphore.internal.h | ||
| mu_semaphore_futex.c | ||
| mu_semaphore_sem.c | ||
| mu_wait.h | ||
| note.h | ||
| notice.c | ||
| once.h | ||
| panic.c | ||
| races.internal.h | ||
| README.cosmo | ||
| time.c | ||
| time.h | ||
| wait_s.internal.h | ||
| waiter.h | ||
| yield.c | ||
DESCRIPTION
*NSYNC is a synchronization primitives library.
LICENSE
Apache 2.0
ORIGIN
git@github.com:google/nsync
commit ac5489682760393fe21bd2a8e038b528442412a7
Author: Mike Burrows <m3b@google.com>
Date: Wed Jun 1 16:47:52 2022 -0700
LOCAL CHANGES
- Fix nsync_mu_unlock() on Apple Silicon
- Add clock parameter to many NSYNC wait APIs
- Time APIs were so good that they're now in libc
- Double linked list API was so good that it's now in libc
- Max delay on sleep should be 20ms (not 4ms) on OpenBSD and NetBSD
- Support Apple's ulock futexes which are internal but nicer than GCD
- Ensure resources such as POSIX semaphores are are released on fork.
- Make contended mutexes go 30% faster by using C11 atomics API. This
lets us use weak cas when appropriate. It also avoids a superfluous
relaxed load on failure. This mostly impacts aarch64, not x86_64.
- Rewrote most of the semaphore and futex system call support code so
it works well with Cosmopolitan's fat runtime portability. *NSYNC's
unit test suite passes on all supported platforms. However the BSDs
currently appear to be overutilizing CPU time compared with others.
This appears to be the fault of the OSes rather than *NSYNC / Cosmo
- Support POSIX thread cancellation. APIs that wait on condition vars
are now cancellation points. In PTHREAD_CANCEL_MASKED mode they may
return ECANCELED. In PTHREAD_CANCEL_DEFERRED mode the POSIX threads
library will unwind the stack to re-acquire locks and free waiters.
On the other hand the *NSYNC APIs for mutexes will now safely block
thread cancellation, but you can still use *NSYNC notes to do that.