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Reduce pthread memory usage

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Justine Tunney 2024-12-24 10:30:59 -08:00
parent ec2db4e40e
commit 93e22c581f
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GPG key ID: BE714B4575D6E328
6 changed files with 75 additions and 58 deletions
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3
libc/thread/posixthread.internal.h
View file

@ -94,7 +94,7 @@ struct PosixThread {
typedef void (*atfork_f)(void);
extern struct Dll *_pthread_list;
extern _Atomic(unsigned) _pthread_count;
extern atomic_uint _pthread_count;
extern struct PosixThread _pthread_static;
extern _Atomic(pthread_key_dtor) _pthread_key_dtor[PTHREAD_KEYS_MAX];
@ -109,6 +109,7 @@ int _pthread_tid(struct PosixThread *) libcesque;
intptr_t _pthread_syshand(struct PosixThread *) libcesque;
long _pthread_cancel_ack(void) libcesque;
void _pthread_decimate(void) libcesque;
void _pthread_free(struct PosixThread *) libcesque paramsnonnull();
void _pthread_lock(void) libcesque;
void _pthread_onfork_child(void) libcesque;
void _pthread_onfork_parent(void) libcesque;

4
libc/thread/pthread_create.c
View file

@ -67,7 +67,7 @@ __static_yoink("_pthread_onfork_prepare");
__static_yoink("_pthread_onfork_parent");
__static_yoink("_pthread_onfork_child");
static void _pthread_free(struct PosixThread *pt) {
void _pthread_free(struct PosixThread *pt) {
// thread must be removed from _pthread_list before calling
unassert(dll_is_alone(&pt->list) && &pt->list != _pthread_list);
@ -84,7 +84,7 @@ static void _pthread_free(struct PosixThread *pt) {
// free any additional upstream system resources
// our fork implementation wipes this handle in child automatically
uint64_t syshand =
atomic_load_explicit(&pt->tib->tib_syshand, memory_order_acquire);
atomic_load_explicit(&pt->tib->tib_syshand, memory_order_relaxed);
if (syshand) {
if (IsWindows())
unassert(CloseHandle(syshand)); // non-inheritable

69
libc/thread/pthread_timedjoin_np.c
View file

@ -62,33 +62,34 @@ static const char *DescribeReturnValue(char buf[30], int err, void **value) {
* @cancelationpoint
*/
static errno_t _pthread_wait(atomic_int *ctid, struct timespec *abstime) {
int x, e;
errno_t err = 0;
if (ctid == &__get_tls()->tib_tid) {
// "If an implementation detects that the value specified by the
// thread argument to pthread_join() refers to the calling thread,
// it is recommended that the function should fail and report an
// [EDEADLK] error." ──Quoth POSIX.1-2017
err = EDEADLK;
} else {
// "If the thread calling pthread_join() is canceled, then the target
// thread shall not be detached." ──Quoth POSIX.1-2017
if (!(err = pthread_testcancel_np())) {
BEGIN_CANCELATION_POINT;
while ((x = atomic_load_explicit(ctid, memory_order_acquire))) {
e = cosmo_futex_wait(ctid, x, !IsWindows() && !IsXnu(), CLOCK_REALTIME,
// "If an implementation detects that the value specified by the
// thread argument to pthread_join() refers to the calling thread,
// it is recommended that the function should fail and report an
// [EDEADLK] error." ──Quoth POSIX.1-2017
if (ctid == &__get_tls()->tib_tid)
return EDEADLK;
// "If the thread calling pthread_join() is canceled, then the target
// thread shall not be detached." ──Quoth POSIX.1-2017
errno_t err;
if ((err = pthread_testcancel_np()))
return err;
BEGIN_CANCELATION_POINT;
int x;
while ((x = atomic_load_explicit(ctid, memory_order_acquire))) {
int e = cosmo_futex_wait(ctid, x, !IsWindows() && !IsXnu(), CLOCK_REALTIME,
abstime);
if (e == -ECANCELED) {
err = ECANCELED;
break;
} else if (e == -ETIMEDOUT) {
err = EBUSY;
break;
}
}
END_CANCELATION_POINT;
if (e == -ECANCELED) {
err = ECANCELED;
break;
} else if (e == -ETIMEDOUT) {
err = EBUSY;
break;
}
}
END_CANCELATION_POINT;
return err;
}
@ -117,12 +118,11 @@ static errno_t _pthread_wait(atomic_int *ctid, struct timespec *abstime) {
errno_t pthread_timedjoin_np(pthread_t thread, void **value_ptr,
struct timespec *abstime) {
int tid;
errno_t err = 0;
errno_t err;
struct PosixThread *pt;
enum PosixThreadStatus status;
pt = (struct PosixThread *)thread;
unassert(thread);
_pthread_ref(pt);
// "The behavior is undefined if the value specified by the thread
// argument to pthread_join() does not refer to a joinable thread."
@ -135,14 +135,23 @@ errno_t pthread_timedjoin_np(pthread_t thread, void **value_ptr,
// specifying the same target thread are undefined."
// ──Quoth POSIX.1-2017
if (!(err = _pthread_wait(&pt->tib->tib_tid, abstime))) {
atomic_store_explicit(&pt->pt_status, kPosixThreadZombie,
memory_order_release);
_pthread_zombify(pt);
if (value_ptr)
*value_ptr = pt->pt_val;
if (atomic_load_explicit(&pt->pt_refs, memory_order_acquire)) {
_pthread_lock();
dll_remove(&_pthread_list, &pt->list);
dll_make_last(&_pthread_list, &pt->list);
atomic_store_explicit(&pt->pt_status, kPosixThreadZombie,
memory_order_release);
_pthread_unlock();
} else {
_pthread_lock();
dll_remove(&_pthread_list, &pt->list);
_pthread_unlock();
_pthread_free(pt);
}
}
_pthread_unref(pt);
STRACE("pthread_timedjoin_np(%d, %s, %s) → %s", tid,
DescribeReturnValue(alloca(30), err, value_ptr),
DescribeTimespec(err ? -1 : 0, abstime), DescribeErrno(err));