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GH-110829: Ensure Thread.join() joins the OS thread (#110848)

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Joining a thread now ensures the underlying OS thread has exited. This is required for safer fork() in multi-threaded processes.

---------

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
This commit is contained in:
Antoine Pitrou 2023-11-04 14:59:24 +01:00 • committed by GitHub
parent a28a3967ab
commit 0e9c364f4a
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GPG key ID: 4AEE18F83AFDEB23
14 changed files with 676 additions and 103 deletions
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71
Python/thread_pthread.h
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@ -235,8 +235,8 @@ pythread_wrapper(void *arg)
return NULL;
}
unsigned long
PyThread_start_new_thread(void (*func)(void *), void *arg)
static int
do_start_joinable_thread(void (*func)(void *), void *arg, pthread_t* out_id)
{
pthread_t th;
int status;
@ -252,7 +252,7 @@ PyThread_start_new_thread(void (*func)(void *), void *arg)
#if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
if (pthread_attr_init(&attrs) != 0)
return PYTHREAD_INVALID_THREAD_ID;
return -1;
#endif
#if defined(THREAD_STACK_SIZE)
PyThreadState *tstate = _PyThreadState_GET();
@ -261,7 +261,7 @@ PyThread_start_new_thread(void (*func)(void *), void *arg)
if (tss != 0) {
if (pthread_attr_setstacksize(&attrs, tss) != 0) {
pthread_attr_destroy(&attrs);
return PYTHREAD_INVALID_THREAD_ID;
return -1;
}
}
#endif
@ -272,7 +272,7 @@ PyThread_start_new_thread(void (*func)(void *), void *arg)
pythread_callback *callback = PyMem_RawMalloc(sizeof(pythread_callback));
if (callback == NULL) {
return PYTHREAD_INVALID_THREAD_ID;
return -1;
}
callback->func = func;
@ -292,11 +292,34 @@ PyThread_start_new_thread(void (*func)(void *), void *arg)
if (status != 0) {
PyMem_RawFree(callback);
return -1;
}
*out_id = th;
return 0;
}
int
PyThread_start_joinable_thread(void (*func)(void *), void *arg,
PyThread_ident_t* ident, PyThread_handle_t* handle) {
pthread_t th = (pthread_t) 0;
if (do_start_joinable_thread(func, arg, &th)) {
return -1;
}
*ident = (PyThread_ident_t) th;
*handle = (PyThread_handle_t) th;
assert(th == (pthread_t) *ident);
assert(th == (pthread_t) *handle);
return 0;
}
unsigned long
PyThread_start_new_thread(void (*func)(void *), void *arg)
{
pthread_t th = (pthread_t) 0;
if (do_start_joinable_thread(func, arg, &th)) {
return PYTHREAD_INVALID_THREAD_ID;
}
pthread_detach(th);
#if SIZEOF_PTHREAD_T <= SIZEOF_LONG
return (unsigned long) th;
#else
@ -304,20 +327,46 @@ PyThread_start_new_thread(void (*func)(void *), void *arg)
#endif
}
int
PyThread_join_thread(PyThread_handle_t th) {
return pthread_join((pthread_t) th, NULL);
}
int
PyThread_detach_thread(PyThread_handle_t th) {
return pthread_detach((pthread_t) th);
}
void
PyThread_update_thread_after_fork(PyThread_ident_t* ident, PyThread_handle_t* handle) {
// The thread id might have been updated in the forked child
pthread_t th = pthread_self();
*ident = (PyThread_ident_t) th;
*handle = (PyThread_handle_t) th;
assert(th == (pthread_t) *ident);
assert(th == (pthread_t) *handle);
}
/* XXX This implementation is considered (to quote Tim Peters) "inherently
hosed" because:
- It does not guarantee the promise that a non-zero integer is returned.
- The cast to unsigned long is inherently unsafe.
- It is not clear that the 'volatile' (for AIX?) are any longer necessary.
*/
unsigned long
PyThread_get_thread_ident(void)
{
PyThread_ident_t
PyThread_get_thread_ident_ex(void) {
volatile pthread_t threadid;
if (!initialized)
PyThread_init_thread();
threadid = pthread_self();
return (unsigned long) threadid;
assert(threadid == (pthread_t) (PyThread_ident_t) threadid);
return (PyThread_ident_t) threadid;
}
unsigned long
PyThread_get_thread_ident(void)
{
return (unsigned long) PyThread_get_thread_ident_ex();
}
#ifdef PY_HAVE_THREAD_NATIVE_ID