try to fix rq/rq#1507

the idea is to port the changes from the current version of rq's monitor_work_horse to the version
introduced by redash. This is a classic example why overriding a method that you don't own is
usually a bad idea. You miss on upstream fixes. Another point is that I'm not even sure if this
custom method is even necessary with the version of rq we're using. Maybe we should investigate it
more

redash/tasks/worker.py

@@ -113,20 +113,20 @@ def monitor_work_horse(self, job, queue):
                 with UnixSignalDeathPenalty(
                     self.job_monitoring_interval, HorseMonitorTimeoutException
                 ):
-                    retpid, ret_val = os.waitpid(self._horse_pid, 0)
+                    retpid, ret_val = self.wait_for_horse()
                 break
             except HorseMonitorTimeoutException:
                 # Horse has not exited yet and is still running.
                 # Send a heartbeat to keep the worker alive.
-                self.heartbeat(self.job_monitoring_interval + 5)
-
-                job.refresh()
+                self.set_current_job_working_time((utcnow() - job.started_at).total_seconds())
 
                 if job.is_cancelled:
                     self.stop_executing_job(job)
 
                 if self.soft_limit_exceeded(job):
                     self.enforce_hard_limit(job)
+
+                self.maintain_heartbeats(job)
             except OSError as e:
                 # In case we encountered an OSError due to EINTR (which is
                 # caused by a SIGINT or SIGTERM signal during
@@ -139,12 +139,21 @@ def monitor_work_horse(self, job, queue):
                 # Send a heartbeat to keep the worker alive.
                 self.heartbeat()
 
+        self.set_current_job_working_time(0)
+        self._horse_pid = 0  # Set horse PID to 0, horse has finished working
         if ret_val == os.EX_OK:  # The process exited normally.
             return
         job_status = job.get_status()
         if job_status is None:  # Job completed and its ttl has expired
             return
-        if job_status not in [JobStatus.FINISHED, JobStatus.FAILED]:
+        elif job_status == JobStatus.STOPPED:
+            # Work-horse killed deliberately
+            self.log.warning('Job stopped by user, moving job to FailedJobRegistry')
+            self.handle_job_failure(
+                job, queue=queue,
+                exc_string="Job stopped by user, work-horse terminated."
+            )
+        elif job_status not in [JobStatus.FINISHED, JobStatus.FAILED]:
 
             if not job.ended_at:
                 job.ended_at = utcnow()