Register job monitor as postfork function

lib/galaxy/jobs/handler.py

@@ -209,7 +209,7 @@ class JobHandlerQueue(Monitors):
             try:
                 # If jobs are locked, there's nothing to monitor and we skip
                 # to the sleep.
-                if not self.app.job_manager.job_lock:
+                if hasattr(self.app, 'job_manager') and not self.app.job_manager.job_lock:
                     self.__monitor_step()
             except Exception:
                 log.exception("Exception in monitor_step")

lib/galaxy/util/monitors.py

@@ -3,6 +3,7 @@ from __future__ import absolute_import
 import logging
 import threading
 
+from galaxy.web.stack import register_postfork_function
 from .sleeper import Sleeper
 
 log = logging.getLogger(__name__)
@@ -27,7 +28,11 @@ class Monitors(object):
         self.sleeper = Sleeper()
         self.monitor_thread = threading.Thread(name=name, target=monitor_func)
         self.monitor_thread.setDaemon(True)
-        if start:
+        self._start = start
+        register_postfork_function(self.start_monitoring)
+
+    def start_monitoring(self):
+        if self._start:
             self.monitor_thread.start()
 
     def stop_monitoring(self):