Worker lifespan

Occasionally, workers that process multiple, memory intensive tasks do not release their used up memory properly, which results in memory usage building up. This is not a bug in MPIRE, but a consequence of Python’s poor garbage collection. To avoid this type of problem you can set the worker lifespan: the number of tasks after which a worker should restart.

with WorkerPool(n_jobs=4) as pool:
    results =, range(100), worker_lifespan=1, chunk_size=1)

In this example each worker is restarted after finishing a single task.


When the worker lifespan has been reached, a worker will finish the current chunk of tasks before restarting. I.e., based on the chunk_size a worker could end up completing more tasks than is allowed by the worker lifespan.