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Make threads faster and more reliable

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This change doubles the performance of thread spawning. That's thanks to
our new stack manager, which allows us to avoid zeroing stacks. It gives
us 15µs spawns rather than 30µs spawns on Linux. Also, pthread_exit() is
faster now, since it doesn't need to acquire the pthread GIL. On NetBSD,
that helps us avoid allocating too many semaphores. Even if that happens
we're now able to survive semaphores running out and even memory running
out, when allocating *NSYNC waiter objects. I found a lot more rare bugs
in the POSIX threads runtime that could cause things to crash, if you've
got dozens of threads all spawning and joining dozens of threads. I want
cosmo to be world class production worthy for 2025 so happy holidays all
This commit is contained in:
Justine Tunney 2024-12-18 04:59:02 -08:00
parent 906bd06a5a
commit 624573207e
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GPG key ID: BE714B4575D6E328
51 changed files with 1006 additions and 321 deletions
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25
libc/proc/fork.c
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@ -17,6 +17,7 @@
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/sig.internal.h"
#include "libc/calls/state.internal.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/calls/struct/timespec.h"
@ -27,6 +28,7 @@
#include "libc/intrin/cxaatexit.h"
#include "libc/intrin/dll.h"
#include "libc/intrin/maps.h"
#include "libc/intrin/stack.h"
#include "libc/intrin/strace.h"
#include "libc/intrin/weaken.h"
#include "libc/nt/files.h"
@ -39,6 +41,7 @@
#include "libc/runtime/syslib.internal.h"
#include "libc/stdio/internal.h"
#include "libc/str/str.h"
#include "libc/thread/itimer.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/thread.h"
#include "third_party/dlmalloc/dlmalloc.h"
@ -104,10 +107,6 @@ static void fork_prepare(void) {
pthread_mutex_lock(&supreme_lock);
if (_weaken(_pthread_onfork_prepare))
_weaken(_pthread_onfork_prepare)();
if (IsWindows()) {
pthread_mutex_lock(&__sig_worker_lock);
__proc_lock();
}
fork_prepare_stdio();
__localtime_lock();
__cxa_lock();
@ -117,12 +116,16 @@ 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();
@ -132,10 +135,6 @@ static void fork_parent(void) {
__cxa_unlock();
__localtime_unlock();
fork_parent_stdio();
if (IsWindows()) {
__proc_unlock();
pthread_mutex_unlock(&__sig_worker_lock);
}
if (_weaken(_pthread_onfork_parent))
_weaken(_pthread_onfork_parent)();
pthread_mutex_unlock(&supreme_lock);
@ -143,6 +142,8 @@ 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(&__rand64_lock_obj);
pthread_mutex_wipe_np(&__fds_lock_obj);
dlmalloc_post_fork_child();
@ -153,8 +154,13 @@ static void fork_child(void) {
pthread_mutex_wipe_np(&__cxa_lock_obj);
pthread_mutex_wipe_np(&__localtime_lock_obj);
if (IsWindows()) {
__proc_wipe();
// we don't bother locking the proc/itimer/sig locks above since
// their state is reset in the forked child. nothing to protect.
__proc_wipe_and_reset();
__itimer_wipe_and_reset();
pthread_mutex_wipe_np(&__sig_worker_lock);
if (_weaken(__sig_init))
_weaken(__sig_init)();
}
if (_weaken(_pthread_onfork_child))
_weaken(_pthread_onfork_child)();
@ -211,6 +217,7 @@ int _fork(uint32_t dwCreationFlags) {
memory_order_relaxed);
}
dll_make_first(&_pthread_list, &pt->list);
atomic_store_explicit(&_pthread_count, 1, memory_order_relaxed);
// get new system thread handle
intptr_t syshand = 0;