- Backported FR #55166 from 5.4 branch (Added process.max to control the number of process FPM can fork)

NEWS

@@ -75,6 +75,8 @@ PHP                                                                        NEWS
   . Fixed bug #53872 (internal corruption of phar). (Hannes)
 
 - PHP-FPM SAPI:
+  . Backported FR #55166 from 5.4 branch (Added process.max to control
+    the number of process FPM can fork). (fat)
   . Backported FR #55181 from 5.4 branch (Enhance security by limiting access
     to user defined extensions). (fat)
   . Backported FR #54098 from 5.4 branch (Lowered process manager

sapi/fpm/fpm/fpm_children.c

@@ -362,6 +362,7 @@ int fpm_children_make(struct fpm_worker_pool_s *wp, int in_event_loop, int nb_to
 	pid_t pid;
 	struct fpm_child_s *child;
 	int max;
+	static int warned = 0;
 
 	if (wp->config->pm == PM_STYLE_DYNAMIC) {
 		if (!in_event_loop) { /* starting */
@@ -373,7 +374,16 @@ int fpm_children_make(struct fpm_worker_pool_s *wp, int in_event_loop, int nb_to
 		max = wp->config->pm_max_children;
 	}
 
-	while (fpm_pctl_can_spawn_children() && wp->running_children < max) {
+	/*
+	 * fork children while:
+	 *   - fpm_pctl_can_spawn_children : FPM is running in a NORMAL state (aka not restart, stop or reload)
+	 *   - wp->running_children < max  : there is less than the max process for the current pool
+	 *   - (fpm_global_config.process_max < 1 || fpm_globals.running_children < fpm_global_config.process_max):
+	 *     if fpm_global_config.process_max is set, FPM has not fork this number of processes (globaly)
+	 */
+	while (fpm_pctl_can_spawn_children() && wp->running_children < max && (fpm_global_config.process_max < 1 || fpm_globals.running_children < fpm_global_config.process_max)) {
+
+		warned = 0;
 		child = fpm_resources_prepare(wp);
 
 		if (!child) {
@@ -406,6 +416,11 @@ int fpm_children_make(struct fpm_worker_pool_s *wp, int in_event_loop, int nb_to
 
 	}
 
+	if (!warned && fpm_global_config.process_max > 0 && fpm_globals.running_children >= fpm_global_config.process_max) {
+		warned = 1;
+		zlog(ZLOG_WARNING, "The maximum number of processes has been reached. Please review your configuration and consider raising 'process.max'");
+	}
+
 	return 1; /* we are done */
 }
 /* }}} */

sapi/fpm/fpm/fpm_conf.c

@@ -66,8 +66,9 @@ static char *fpm_conf_set_syslog_facility(zval *value, void **config, intptr_t o
 struct fpm_global_config_s fpm_global_config = {
 	.daemonize = 1,
 #ifdef HAVE_SYSLOG_H
-	.syslog_facility = -1
+	.syslog_facility = -1,
 #endif
+	.process_max = 0,
 };
 static struct fpm_worker_pool_s *current_wp = NULL;
 static int ini_recursion = 0;
@@ -79,6 +80,7 @@ static struct ini_value_parser_s ini_fpm_global_options[] = {
 	{ "emergency_restart_threshold", &fpm_conf_set_integer,         GO(emergency_restart_threshold) },
 	{ "emergency_restart_interval",  &fpm_conf_set_time,            GO(emergency_restart_interval) },
 	{ "process_control_timeout",     &fpm_conf_set_time,            GO(process_control_timeout) },
+	{ "process.max",                 &fpm_conf_set_integer,         GO(process_max) },
 	{ "daemonize",                   &fpm_conf_set_boolean,         GO(daemonize) },
 	{ "pid",                         &fpm_conf_set_string,          GO(pid_file) },
 	{ "error_log",                   &fpm_conf_set_string,          GO(error_log) },
@@ -1014,6 +1016,11 @@ static int fpm_conf_post_process(TSRMLS_D) /* {{{ */
 
 	fpm_globals.log_level = fpm_global_config.log_level;
 
+	if (fpm_global_config.process_max < 0) {
+		zlog(ZLOG_ERROR, "process_max can't be negative");
+		return -1;
+	}
+
 	if (!fpm_global_config.error_log) {
 		fpm_global_config.error_log = strdup("log/php-fpm.log");
 	}
@@ -1394,6 +1401,7 @@ static void fpm_conf_dump() /* {{{ */
 	zlog(ZLOG_NOTICE, "\tsyslog.facility = %d",             fpm_global_config.syslog_facility); /* FIXME: convert to string */
 #endif
 	zlog(ZLOG_NOTICE, "\tprocess_control_timeout = %ds",    fpm_global_config.process_control_timeout);
+	zlog(ZLOG_NOTICE, "\tprocess.max = %d",                 fpm_global_config.process_max);
 	zlog(ZLOG_NOTICE, "\temergency_restart_interval = %ds", fpm_global_config.emergency_restart_interval);
 	zlog(ZLOG_NOTICE, "\temergency_restart_threshold = %d", fpm_global_config.emergency_restart_threshold);
 	zlog(ZLOG_NOTICE, "\trlimit_files = %d",                fpm_global_config.rlimit_files);

sapi/fpm/fpm/fpm_conf.h

@@ -32,6 +32,7 @@ struct fpm_global_config_s {
 #endif
 	int rlimit_files;
 	int rlimit_core;
+	int process_max;
 };
 
 extern struct fpm_global_config_s fpm_global_config;

sapi/fpm/php-fpm.conf.in

@@ -69,6 +69,13 @@
 ; Default Value: 0
 ;process_control_timeout = 0
 
+; The maximum number of processes FPM will fork. This has been design to control
+; the global number of processes when using dynamic PM within a lot of pools.
+; Use it with caution.
+; Note: A value of 0 indicates no limit
+; Default Value: 0
+; process.max = 128
+
 ; Send FPM to background. Set to 'no' to keep FPM in foreground for debugging.
 ; Default Value: yes
 ;daemonize = yes