In a Ubuntu instance in GCE, I have 614 unpigz child processes under dockerd when examining the processes via ps afx. Normal? After restarting Docker, is there a chance that it gets reproduced...?

  • 1
    What are you running in docker? Apr 11 '19 at 18:01
  • Couple of node processes in a phusion baseimage based image. In the host side there is an automation that keeps sure that the latest image from the registry is being used. I don’t think it is related to the image internals since the container has been upgraded recently and that didn’t affect the situation. Apr 11 '19 at 18:08

This is a BUG actually (see https://github.com/moby/moby/issues/38608). These processes will disappear after Docker service restart, but they will be created again as long as you use Docker's ADD *.tar.gz (or similar) feature.


Inefficient but not dangerous. You make the decision of whether lots of processes like this is healthy for your environment.

pigz is a parallel implementation of gzip. The default maximum for --processes is the number of online processors, and each container sees all the CPUs of the system. They will compete for CPU and I/O, so may pile up and thrash the Linux scheduler a bit.

Optimum number of process is probably closer to 2x the number of CPUs. If you run lots of pigz at once, it may be more effecient to serialize those, reduce --processes, or use regular not-threaded gunzip.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.