Tasks can be terminated if any of the following are met:

  • Task has run longer than its timeout

  • Task’s end_cond is true

  • Scheduler is immediately shutting down

This section discusses these ways to terminate tasks.


Only async, thread and process tasks can be terminated. Read more about the execution methods: execution method handbook <handbook-execution>.


If you use threaded execution, you should periodically check the termination flag status and raise termination exception if it is set in order to correctly handle the termination:

from rocketry.args import TerminationFlag
from rocketry.exc import TaskTerminationException

def do_thread(flag=TerminationFlag()):
    while True:
        ... # Do something
        if flag.is_set():
            raise TaskTerminationException()


If you use async execution, you should release the execution in order to make it possible for the scheduler to terminate it:

import asyncio

async def do_async():
    ... # Do things
    await asyncio.sleep(0)
    ... # Do more


Timeout defines how long the task may run. It can be set on session level and on task level. Task level timeout overrides the session setting so if a task does not have timeout specified the session setting is used instead.

To set it on task level:

@app.task(timeout="1 hour", execution="process")
def do_things():

To set it on session level:

from rocketry import Rocketry

app = Rocketry(config={"timeout": 0.1})

@app.task(timeout="1 hour", execution="process")
def do_things():

The timeout can be as:

  • int or float (number of seconds)

  • string (timedelta string)

  • datetime.timedelta

End Condition

End condition is a condition that when true, the task is terminated. This is useful to prevent some tasks to run outside their intended period. For example, you may want to kill all running less important tasks when the actual production starts.

For example, this task will be terminated if it is running between 08:00 and 18:00 (8 am to 6 pm):

from rocketry.conds import time_of_day

@app.task(end_cond=time_of_day.between("08:00", "18:00"))
def do_things():

Scheduler Shutdown

If scheduler shuts down with no errors (either shut_down was called or the scheduler shut condition was reached), the scheduler waits for the running tasks to finish or to reach their timeout or end condition.

However, the scheduler will terminate all tasks during shutdown if:

  • Scheduler encountered a fatal error

  • The configuration instant_shutdown is True

  • session.shut_down(force=True) was called

  • session.shut_down() was called twice