fix: #3865 ensure pm2 never run simultaneous gracefullExit, prevent dump file corruption

Author: wallet77

lib/Daemon.js

@@ -331,6 +331,12 @@ Daemon.prototype.sendReady = function(cb) {
 Daemon.prototype.gracefullExit = function() {
   var that = this;
 
+  // never execute multiple gracefullExit simultaneously
+  // this can lead to loss of some apps in dump file
+  if (this.isExiting) return
+
+  this.isExiting = true
+
   God.bus.emit('pm2:kill', {
     status : 'killed',
     msg    : 'pm2 has been killed by SIGNAL'
@@ -352,6 +358,7 @@ Daemon.prototype.gracefullExit = function() {
         fs.unlinkSync(that.pid_path);
       } catch(e) {}
       setTimeout(function() {
+        that.isExiting = false
         console.log('Exited peacefully');
         process.exit(cst.SUCCESS_EXIT);
       }, 2);