diff options
Diffstat (limited to 'thread_pthread.c')
| -rw-r--r-- | thread_pthread.c | 42 |
1 files changed, 41 insertions, 1 deletions
diff --git a/thread_pthread.c b/thread_pthread.c index 209ed6781c..92ec66af1e 100644 --- a/thread_pthread.c +++ b/thread_pthread.c @@ -1911,7 +1911,7 @@ rb_sigwait_fd_get(const rb_thread_t *th) return signal_self_pipe.normal[0]; } } - return -1; /* avoid thundering herd */ + return -1; /* avoid thundering herd and work stealing/starvation */ } void @@ -1996,6 +1996,43 @@ rb_sigwait_sleep(rb_thread_t *th, int sigwait_fd, const struct timespec *ts) } } +/* + * This function does not exclusively acquire sigwait_fd, so it + * cannot safely read from it. However, it can be woken up in + * 4 ways: + * + * 1) ubf_select (from another thread) + * 2) rb_thread_wakeup_timer_thread (from signal handler) + * 3) any unmasked signal hitting the process + * 4) periodic ubf timer wakeups (after 3) + */ +static void +native_ppoll_sleep(rb_thread_t *th, rb_hrtime_t *rel) +{ + rb_native_mutex_lock(&th->interrupt_lock); + th->unblock.func = ubf_select; + th->unblock.arg = th; + rb_native_mutex_unlock(&th->interrupt_lock); + + GVL_UNLOCK_BEGIN(th); + if (!RUBY_VM_INTERRUPTED(th->ec)) { + struct pollfd pfd; + struct timespec ts; + + pfd.fd = signal_self_pipe.normal[0]; /* sigwait_fd */ + pfd.events = POLLIN; + (void)ppoll(&pfd, 1, rb_hrtime2timespec(&ts, rel), 0); + + /* + * do not read the fd, here, let uplevel callers or other threads + * that, otherwise we may steal and starve other threads + */ + } + unblock_function_clear(th); + unregister_ubf_list(th); + GVL_UNLOCK_END(th); +} + static void native_sleep(rb_thread_t *th, rb_hrtime_t *rel) { @@ -2020,6 +2057,9 @@ native_sleep(rb_thread_t *th, rb_hrtime_t *rel) rb_sigwait_fd_put(th, sigwait_fd); rb_sigwait_fd_migrate(th->vm); } + else if (th == th->vm->main_thread) { /* always able to handle signals */ + native_ppoll_sleep(th, rel); + } else { native_cond_sleep(th, rel); } |