feat: use real-time signal

Author: dunglas

Zend/zend_execute_API.c

@@ -1324,7 +1324,7 @@ static void zend_timeout_handler(int dummy, siginfo_t *si, void *uc) /* {{{ */
 {
 	if (si->si_value.sival_ptr != &EG(timer)) {
 #ifdef TIMER_DEBUG
-		fprintf(stderr, "Executing previous handler (if set) for unexpected signal SIGIO received on thread %d\n", (pid_t) syscall(SYS_gettid));
+		fprintf(stderr, "Executing previous handler (if set) for unexpected signal SIGRTMIN received on thread %d\n", (pid_t) syscall(SYS_gettid));
 #endif
 
 		if (EG(oldact).sa_sigaction) {
@@ -1449,9 +1449,9 @@ static void zend_set_timeout_ex(zend_long seconds, bool reset_signals) /* {{{ */
 		act.sa_sigaction = zend_timeout_handler;
 		sigemptyset(&act.sa_mask);
 		act.sa_flags = SA_ONSTACK | SA_SIGINFO;
-		sigaction(SIGIO, &act, NULL);
+		sigaction(SIGRTMIN, &act, NULL);
 		sigemptyset(&sigset);
-		sigaddset(&sigset, SIGIO);
+		sigaddset(&sigset, SIGRTMIN);
 		sigprocmask(SIG_UNBLOCK, &sigset, NULL);
 	}
 #elif defined(HAVE_SETITIMER)

Zend/zend_timer.c

@@ -38,13 +38,7 @@ ZEND_API void zend_timer_init(void) /* {{{ */
 	struct sigevent sev;
 	sev.sigev_notify = SIGEV_THREAD_ID;
 	sev.sigev_value.sival_ptr = &EG(timer);
-	// The chosen signal must:
-	// 1. not be used internally by libc
-	// 2. be allowed to happen spuriously without consequences
-	// 3. not be commonly used by applications, this excludes SIGALRM, SIGUSR1 and SIGUSR2
-	// 4. not be used by profilers, this excludes SIGPROF
-	// 5. not be used internally by runtimes of programs that can embed PHP, this excludes SIGURG, which is used by Go
-	sev.sigev_signo = SIGIO;
+	sev.sigev_signo = SIGRTMIN;
 	sev.sigev_notify_thread_id = (pid_t) syscall(SYS_gettid);
 
 	EG(pid) = getpid();