python - Measuring Celery task execution time

Question

I have converted a standalone batch job to use celery for dispatching the work to be done. I'm using RabbitMQ. Everything is running on a single machine and no other processes are using the RabbitMQ instance. My script just creates a bunch of tasks which are processed by workers.

Is there a simple way to measure the time from the start of my script until all tasks are finished? I know that this a bit complicated by design when using message queues. But I don't want to do it in production, just for testing and getting a performance estimation.

Answer 1

You could use celery signals, functions registered will be called before and after a task is executed, it is trivial to measure elapsed time:

from time import time
from celery.signals import task_prerun, task_postrun


d = {}

@task_prerun.connect
def task_prerun_handler(signal, sender, task_id, task, args, kwargs, **extras):
    d[task_id] = time()


@task_postrun.connect
def task_postrun_handler(signal, sender, task_id, task, args, kwargs, retval, state, **extras):
    try:
        cost = time() - d.pop(task_id)
    except KeyError:
        cost = -1
    print task.__name__, cost