Defunct process leading high CPU usage

[L3o-pold]

After some usage, seems that manet will let some zombie process.
It leads to high CPU usage after some times.

Here is an example of a manet instance runned since 2 hours.

ps -aux

root 1 0.1 0.3 939332 65224 ? Ssl 14:21 0:06 node /usr/local
root 398 0.0 0.0 0 0 ? Z 14:28 0:00 [node] <defunct
root 405 0.0 0.0 0 0 ? Z 14:28 0:00 [phantomjs] <de

I saw this thread that could help https://stackoverflow.com/questions/37825670/why-nodejs-spawn-process-become-defunct-until-parent-exited.

I am not sure how to fix it, and I couldn't reproduce this behavior outside of our production environment (xenial/puppet with docker and nodejs:8 official image).