# Buggy code
def launchTask(self, driver, task):
    """
    Invoked by SchedulerDriver when a Mesos task should be launched by this executor
    """

    def runTask():
        log.debug("Running task %s", task.task_id.value)
        sendUpdate(mesos_pb2.TASK_RUNNING)
        popen = runJob(pickle.loads(task.data))
        self.runningTasks[task.task_id.value] = popen.pid
        try:
            exitStatus = popen.wait()
            if 0 == exitStatus:
                sendUpdate(mesos_pb2.TASK_FINISHED)
            elif -9 == exitStatus:
                sendUpdate(mesos_pb2.TASK_KILLED)
            else:
                sendUpdate(mesos_pb2.TASK_FAILED, message=str(exitStatus))
        except:
            exc_type, exc_value, exc_trace = sys.exc_info()
            sendUpdate(
                mesos_pb2.TASK_FAILED,
                message=str(traceback.format_exception_only(exc_type, exc_value)),
            )
        finally:
            del self.runningTasks[task.task_id.value]

    def runJob(job):
        """
        :type job: toil.batchSystems.mesos.ToilJob

        :rtype: subprocess.Popen
        """
        if job.userScript:
            job.userScript.register()
        log.debug("Invoking command: '%s'", job.command)
        with self.popenLock:
            return subprocess.Popen(
                job.command, shell=True, env=dict(os.environ, **job.environment)
            )

    def sendUpdate(taskState, message=""):
        log.debug("Sending status update ...")
        status = mesos_pb2.TaskStatus()
        status.task_id.value = task.task_id.value
        status.message = message
        status.state = taskState
        driver.sendStatusUpdate(status)
        log.debug("Sent status update")

    thread = threading.Thread(target=runTask)
    thread.start()


# Traceback (ValueError)
Failed to call scheduler's statusUpdate
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/toil/batchSystems/mesos/batchSystem.py", line 458, in statusUpdate
exitStatus = int(update.message)
ValueError: invalid literal for int() with base 10: ''

# Fixed code
def launchTask(self, driver, task):
    """
    Invoked by SchedulerDriver when a Mesos task should be launched by this executor
    """

    def runTask():
        log.debug("Running task %s", task.task_id.value)
        sendUpdate(mesos_pb2.TASK_RUNNING)
        try:
            popen = runJob(pickle.loads(task.data))
            self.runningTasks[task.task_id.value] = popen.pid
            try:
                exitStatus = popen.wait()
                if 0 == exitStatus:
                    sendUpdate(mesos_pb2.TASK_FINISHED)
                elif -9 == exitStatus:
                    sendUpdate(mesos_pb2.TASK_KILLED)
                else:
                    sendUpdate(mesos_pb2.TASK_FAILED, message=str(exitStatus))
            finally:
                del self.runningTasks[task.task_id.value]
        except:
            exc_info = sys.exc_info()
            log.error("Exception while running task:", exc_info=exc_info)
            exc_type, exc_value, exc_trace = exc_info
            sendUpdate(
                mesos_pb2.TASK_FAILED,
                message="".join(traceback.format_exception_only(exc_type, exc_value)),
            )

    def runJob(job):
        """
        :type job: toil.batchSystems.mesos.ToilJob

        :rtype: subprocess.Popen
        """
        if job.userScript:
            job.userScript.register()
        log.debug("Invoking command: '%s'", job.command)
        with self.popenLock:
            return subprocess.Popen(
                job.command, shell=True, env=dict(os.environ, **job.environment)
            )

    def sendUpdate(taskState, message=""):
        log.debug("Sending status update ...")
        status = mesos_pb2.TaskStatus()
        status.task_id.value = task.task_id.value
        status.message = message
        status.state = taskState
        driver.sendStatusUpdate(status)
        log.debug("Sent status update")

    thread = threading.Thread(target=runTask)
    thread.start()