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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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43
libc/proc/fork.c
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@ -114,6 +114,8 @@ static void fork_prepare(void) {
fork_prepare_stdio();
__localtime_lock();
__dlopen_lock();
if (_weaken(cosmo_stack_lock))
_weaken(cosmo_stack_lock)();
__cxa_lock();
__gdtoa_lock1();
__gdtoa_lock();
@ -121,16 +123,12 @@ static void fork_prepare(void) {
dlmalloc_pre_fork();
__fds_lock();
_pthread_mutex_lock(&__rand64_lock_obj);
if (_weaken(cosmo_stack_lock))
_weaken(cosmo_stack_lock)();
__maps_lock();
LOCKTRACE("READY TO LOCK AND ROLL");
}
static void fork_parent(void) {
__maps_unlock();
if (_weaken(cosmo_stack_unlock))
_weaken(cosmo_stack_unlock)();
_pthread_mutex_unlock(&__rand64_lock_obj);
__fds_unlock();
dlmalloc_post_fork_parent();
@ -138,6 +136,8 @@ static void fork_parent(void) {
__gdtoa_unlock();
__gdtoa_unlock1();
__cxa_unlock();
if (_weaken(cosmo_stack_unlock))
_weaken(cosmo_stack_unlock)();
__dlopen_unlock();
__localtime_unlock();
fork_parent_stdio();
@ -148,8 +148,6 @@ static void fork_parent(void) {
static void fork_child(void) {
nsync_mu_semaphore_sem_fork_child();
if (_weaken(cosmo_stack_wipe))
_weaken(cosmo_stack_wipe)();
_pthread_mutex_wipe_np(&__dlopen_lock_obj);
_pthread_mutex_wipe_np(&__rand64_lock_obj);
_pthread_mutex_wipe_np(&__fds_lock_obj);
@ -159,6 +157,8 @@ static void fork_child(void) {
fork_child_stdio();
_pthread_mutex_wipe_np(&__pthread_lock_obj);
_pthread_mutex_wipe_np(&__cxa_lock_obj);
if (_weaken(cosmo_stack_wipe))
_weaken(cosmo_stack_wipe)();
_pthread_mutex_wipe_np(&__localtime_lock_obj);
if (IsWindows()) {
// we don't bother locking the proc/itimer/sig locks above since
@ -204,11 +204,11 @@ int _fork(uint32_t dwCreationFlags) {
struct CosmoTib *tib = __get_tls();
struct PosixThread *pt = (struct PosixThread *)tib->tib_pthread;
tid = IsLinux() || IsXnuSilicon() ? dx : sys_gettid();
atomic_store_explicit(&tib->tib_tid, tid, memory_order_relaxed);
atomic_store_explicit(&pt->ptid, tid, memory_order_relaxed);
atomic_init(&tib->tib_tid, tid);
atomic_init(&pt->ptid, tid);
// tracing and kisdangerous need this lock wiped a little earlier
atomic_store_explicit(&__maps.lock.word, 0, memory_order_relaxed);
atomic_init(&__maps.lock.word, 0);
/*
* it's now safe to call normal functions again
@ -218,14 +218,10 @@ int _fork(uint32_t dwCreationFlags) {
// we can't free() them since we're monopolizing all locks
// we assume the operating system already reclaimed system handles
dll_remove(&_pthread_list, &pt->list);
for (e = dll_first(_pthread_list); e; e = dll_next(_pthread_list, e)) {
atomic_store_explicit(&POSIXTHREAD_CONTAINER(e)->pt_status,
kPosixThreadZombie, memory_order_relaxed);
atomic_store_explicit(&POSIXTHREAD_CONTAINER(e)->tib->tib_syshand, 0,
memory_order_relaxed);
}
struct Dll *old_threads = _pthread_list;
_pthread_list = 0;
dll_make_first(&_pthread_list, &pt->list);
atomic_store_explicit(&_pthread_count, 1, memory_order_relaxed);
atomic_init(&_pthread_count, 1);
// get new system thread handle
intptr_t syshand = 0;
@ -236,16 +232,27 @@ int _fork(uint32_t dwCreationFlags) {
GetCurrentProcess(), &syshand, 0, false,
kNtDuplicateSameAccess);
}
atomic_store_explicit(&tib->tib_syshand, syshand, memory_order_relaxed);
atomic_init(&tib->tib_syshand, syshand);
// we can't be canceled if the canceler no longer exists
atomic_store_explicit(&pt->pt_canceled, false, memory_order_relaxed);
atomic_init(&pt->pt_canceled, false);
// forget locks
memset(tib->tib_locks, 0, sizeof(tib->tib_locks));
// run user fork callbacks
fork_child();
// free threads
if (_weaken(_pthread_free)) {
while ((e = dll_first(old_threads))) {
pt = POSIXTHREAD_CONTAINER(e);
atomic_init(&pt->tib->tib_syshand, 0);
dll_remove(&old_threads, e);
_weaken(_pthread_free)(pt);
}
}
STRACE("fork() → 0 (child of %d; took %ld us)", parent, micros);
} else {
// this is the parent process