do no re-create persisted channels in forked child process

src/php/ext/grpc/channel.c

@@ -586,6 +586,13 @@ void php_grpc_delete_persistent_list_entry(char *key, php_grpc_int key_len
   gpr_mu_unlock(&global_persistent_list_mu);
 }
 
+// Clean all channels in the persistent list
+// Called at post fork
+void php_grpc_clean_persistent_list(TSRMLS_D) {
+  zend_hash_clean(&grpc_persistent_list);
+  zend_hash_clean(&grpc_target_upper_bound_map);
+}
+
 // A destructor associated with each list entry from the persistent list
 static void php_grpc_channel_plink_dtor(php_grpc_zend_resource *rsrc
                                         TSRMLS_DC) {
@@ -615,12 +622,11 @@ static void php_grpc_target_bound_dtor(php_grpc_zend_resource *rsrc
 #ifdef GRPC_PHP_DEBUG
 
 /**
-* Clean all channels in the persistent. Test only.
+* Clean all channels in the persistent
 * @return void
 */
 PHP_METHOD(Channel, cleanPersistentList) {
-  zend_hash_clean(&grpc_persistent_list);
-  zend_hash_clean(&grpc_target_upper_bound_map);
+  php_grpc_clean_persistent_list(TSRMLS_C);
 }
 
 char *grpc_connectivity_state_name(grpc_connectivity_state state) {

src/php/ext/grpc/channel.h

@@ -60,6 +60,8 @@ void generate_sha1_str(char *sha1str, char *str, php_grpc_int len);
 void php_grpc_delete_persistent_list_entry(char *key, php_grpc_int key_len
                                            TSRMLS_DC);
 
+void php_grpc_clean_persistent_list(TSRMLS_D);
+
 typedef struct _channel_persistent_le {
   grpc_channel_wrapper *channel;
 } channel_persistent_le_t;

src/php/ext/grpc/php_grpc.c

@@ -206,9 +206,8 @@ void postfork_child() {
   grpc_init();
   grpc_php_init_completion_queue(TSRMLS_C);
 
-  // re-create grpc_channel and point wrapped to it
-  // unlock wrapped grpc channel mutex
-  restart_channels();
+  // clean all channels in the persistent list
+  php_grpc_clean_persistent_list(TSRMLS_C);
 }
 
 void postfork_parent() {