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Remove __pthread_detached_exit in favor of __emscripten_thread_cleanup. NFC. #15605

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Merged
merged 3 commits into from
Jan 11, 2022
+3 −14
Merged

Remove __pthread_detached_exit in favor of __emscripten_thread_cleanup. NFC. #15605

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10ebc0e
Remove __pthread_detached_exit in favor of __emscripten_thread_cleanu…
kleisauke Nov 23, 2021
1a19bb6
Fix function signature mismatch
kleisauke Nov 23, 2021
2eaa7d3
Revert detachedExit -> exit change
kleisauke Nov 23, 2021
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11 changes: 0 additions & 11 deletions src/library_pthread.js
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Original file line number Diff line number Diff line change
Expand Up @@ -275,11 +275,6 @@ var LibraryPThread = {
err('Thread ' + d['threadId'] + ': ' + d['text']);
} else if (cmd === 'alert') {
alert('Thread ' + d['threadId'] + ': ' + d['text']);
} else if (cmd === 'detachedExit') {
#if ASSERTIONS
assert(worker.pthread);
#endif
PThread.returnWorkerToPool(worker);
} else if (d.target === 'setimmediate') {
// Worker wants to postMessage() to itself to implement setImmediate()
// emulation.
Expand Down Expand Up @@ -834,12 +829,6 @@ var LibraryPThread = {
return 0;
},

__pthread_detached_exit: function() {
// Called at the end of pthread_exit (which occurs also when leaving the
// thread main function) if an only if the thread is in a detached state.
postMessage({ 'cmd': 'detachedExit' });
},

// Returns 0 on success, or one of the values -ETIMEDOUT, -EWOULDBLOCK or -EINVAL on error.
emscripten_futex_wait__deps: ['emscripten_main_thread_process_queued_calls'],
emscripten_futex_wait: function(addr, val, timeout) {
Expand Down
4 changes: 2 additions & 2 deletions system/lib/pthread/pthread_create.c
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Expand Up @@ -25,7 +25,7 @@
extern int __pthread_create_js(struct pthread *thread, const pthread_attr_t *attr, void *(*start_routine) (void *), void *arg);
extern void _emscripten_thread_init(int, int, int);
extern int _emscripten_default_pthread_stack_size();
extern void __pthread_detached_exit();
extern void __emscripten_thread_cleanup(pthread_t thread);
extern void* _emscripten_tls_base();
extern int8_t __dso_handle;

Expand Down Expand Up @@ -236,7 +236,7 @@ void _emscripten_thread_exit(void* result) {
// object and we are done.
if (state == DT_DETACHED) {
self->detach_state = DT_EXITED;
__pthread_detached_exit();
__emscripten_thread_cleanup(self);
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I was thinking about doing this .. but I was slightly worried about free'ing the stack being used by the current thread.

Seems a little dangerous. I don't come up with better solution yet but I was thinking maybe we could instead call this from worker.js? (i.e. once the stack is unwound all the way)?

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IIUC, __emscripten_thread_free_data was also called by the detachedExit/__pthread_detached_exit, so this PR should be completely non-functional (except that it now sends the cleanupThread command, which will also eventually call returnWorkerToPool/__emscripten_thread_free_data).

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@sbc100 sbc100 Nov 23, 2021 •
edited
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IIUC, In the current code, when __pthread_detached_exit is called the detachedExit command is sent back to the main thread which ends up freeing the data, so the data is not freed on the exit'ing thread at all.

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Oh wait, I see that __emscripten_thread_cleanup also posts a message back to the main thread.. so I agree this should be and NFC. Thanks for clarifying!

} else {
self->detach_state = DT_EXITING;
// wake any threads that might be waiting for us to exit
Expand Down
2 changes: 1 addition & 1 deletion system/lib/pthread/pthread_join.c
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Expand Up @@ -10,7 +10,7 @@
#include <pthread.h>

extern int __pthread_join_js(pthread_t t, void **res, int tryjoin);
extern int __emscripten_thread_cleanup(pthread_t t);
extern void __emscripten_thread_cleanup(pthread_t t);

static int __pthread_join_internal(pthread_t t, void **res) {
if (t->self != t) {
Expand Down