title: Python-Celery increase concurrency on worker
body: <p><strong>TL;DR</strong></p>
  
  <p>Is it possible to increase or decrease concurrency on a <strong>running</strong> Celery worker <strong>without</strong> restarting it?</p>
  
  <p>I'm using celery 4.0.0 with RabbitMQ as a broker on ubuntu 14.10</p>
  
  <p><strong>My Usecase</strong></p>
  
  <p>I am frequently facing a large queue of tasks, most of which primarily execute an HTTP-Request and do some minor processing. I have the worker running on a fairly powerful machine and would like to maximize resource utilization on it. This is not a problem most of the time, except when dealing with these large number of HTTP-Requests, which might timeout or take a very long time to respond etc. When dealing with these, I'd like to temporarily increase the <code>--concurrency</code>-parameter, without actually having to restart the worker.</p>
  
  <p>Currently I'm running celery with <code>--concurrency  150</code>, but this will only get the servers bottleneck (CPU) to about ~10% utilization. I suppose one solution would be to spawn another 150-concurrency worker for that time period and kill it later, but that might add complexity down the road. I'd like to stick to 1 worker/machine if at all possible.</p>