fix: wait for all child processes to terminate (fixes issue remy#1476)

lib/monitor/run.js

@@ -16,6 +16,27 @@ var psTree = require('pstree.remy');
 var path = require('path');
 var signals = require('./signals');
 
+function waitForOldKids(oldKids, callback) {
+  if (oldKids) {
+    // check if all previous kids have been terminated
+    exec('kill -0  ' + oldKids.join(' '), (error) => {
+      const returnCode = error ? error.code : 0;
+      if (returnCode < 126) { // ignore command not found error
+        const stillRunningKids = oldKids.length - returnCode;
+        if (stillRunningKids > 0) {
+          utils.log.status('still waiting for ' + stillRunningKids +
+            ' child process(es) to finish...');
+          setTimeout(waitForOldKids.bind(this, oldKids, callback), 100);
+          return;
+        }
+      }
+      callback();
+    });
+  } else {
+    callback();
+  }
+}
+
 function run(options) {
   var cmd = config.command.raw;
 
@@ -343,15 +364,21 @@ function kill(child, signal, callback) {
     const sig = signal.replace('SIG', '');
     psTree(child.pid, function (err, kids) {
       if (psTree.hasPS) {
-        spawn('kill', ['-s', sig, child.pid].concat(kids))
-          .on('close', callback);
+        spawn('kill', ['-s', sig].concat(kids))
+          .on('close', waitForOldKids.bind(this, kids, function () {
+            spawn('kill', ['-s', sig, child.pid])
+              .on('close', callback);
+          }));
       } else {
         // make sure we kill from smallest to largest
-        const pids = kids.concat(child.pid).sort();
+        const pids = kids.sort();
         pids.forEach(pid => {
           exec('kill -' + signals[signal] + ' ' + pid, () => { });
         });
-        callback();
+        waitForOldKids(kids, function () {
+          exec('kill -' + signals[signal] + ' ' + child.pid, () => { });
+          callback();
+        })
       }
     });