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mjit: get rid of memory leak in pause+resume loop

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pthread_atfork is not idempotent and repeatedly calling it
causes it to register the same hook repeatedly; leading to
unbound memory growth.

Ruby already has a (confusing-named) internal API for to call
in the forked child process: rb_thread_atfork
Call the MJIT child_after_fork hook inside that to prevent
unbound growth with the following loop:

    loop do
      RubyVM::MJIT.pause
      RubyVM::MJIT.resume
    end

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63884 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
normal 2018-07-08 07:27:24 +00:00
parent a1e589498d
commit c93adfc170
4 changed files with 13 additions and 10 deletions
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14
mjit.c
View file

@ -117,7 +117,7 @@ extern void rb_native_cond_signal(rb_nativethread_cond_t *cond);
extern void rb_native_cond_broadcast(rb_nativethread_cond_t *cond);
extern void rb_native_cond_wait(rb_nativethread_cond_t *cond, rb_nativethread_lock_t *mutex);
extern int rb_thread_create_mjit_thread(void (*child_hook)(void), void (*worker_func)(void));
extern int rb_thread_create_mjit_thread(void (*worker_func)(void));
/* process.c */
rb_pid_t ruby_waitpid_locked(rb_vm_t *, rb_pid_t, int *status, int options,
@ -1319,11 +1319,13 @@ init_header_filename(void)
/* This is called after each fork in the child in to switch off MJIT
engine in the child as it does not inherit MJIT threads. */
static void
child_after_fork(void)
void
mjit_child_after_fork(void)
{
verbose(3, "Switching off MJIT in a forked child");
mjit_enabled = FALSE;
if (mjit_enabled) {
verbose(3, "Switching off MJIT in a forked child");
mjit_enabled = FALSE;
}
/* TODO: Should we initiate MJIT in the forked Ruby. */
}
@ -1433,7 +1435,7 @@ start_worker(void)
stop_worker_p = FALSE;
worker_stopped = FALSE;
if (!rb_thread_create_mjit_thread(child_after_fork, worker)) {
if (!rb_thread_create_mjit_thread(worker)) {
mjit_enabled = FALSE;
rb_native_mutex_destroy(&mjit_engine_mutex);
rb_native_cond_destroy(&mjit_pch_wakeup);

3
thread.c
View file

@ -4276,6 +4276,8 @@ terminate_atfork_i(rb_thread_t *th, const rb_thread_t *current_th)
}
}
/* mjit.c */
void mjit_child_after_fork(void);
void
rb_thread_atfork(void)
{
@ -4286,6 +4288,7 @@ rb_thread_atfork(void)
/* We don't want reproduce CVE-2003-0900. */
rb_reset_random_seed();
mjit_child_after_fork();
}
static void

4
thread_pthread.c
View file

@ -1767,14 +1767,12 @@ mjit_worker(void *arg)
/* Launch MJIT thread. Returns FALSE if it fails to create thread. */
int
rb_thread_create_mjit_thread(void (*child_hook)(void), void (*worker_func)(void))
rb_thread_create_mjit_thread(void (*worker_func)(void))
{
pthread_attr_t attr;
pthread_t worker_pid;
int ret = FALSE;
pthread_atfork(NULL, NULL, child_hook);
if (pthread_attr_init(&attr) != 0) return ret;
/* jit_worker thread is not to be joined */

2
thread_win32.c
View file

@ -790,7 +790,7 @@ mjit_worker(void *arg)
/* Launch MJIT thread. Returns FALSE if it fails to create thread. */
int
rb_thread_create_mjit_thread(void (*child_hook)(void), void (*worker_func)(void))
rb_thread_create_mjit_thread(void (*worker_func)(void))
{
size_t stack_size = 4 * 1024; /* 4KB is the minimum commit size */
HANDLE thread_id = w32_create_thread(stack_size, mjit_worker, worker_func);