On container exit/termination lfsmount process remains in the process table as defunct

[jadolg]

When the container is exited the process remains there until the plugin is disabled.

root      177994  177974  0 11:22 ?        00:00:00 lfsmount /mnt/lizardfs/ -H 10.231.217.39 -P 9421 -S /ppp
root      178467  177974  0 11:22 ?        00:00:00 [lfsmount] <defunct>

I'm guessing I need to somehow detach the parent process from it so it can die without problems.
What do you think @aNeutrino ?

[jadolg]

This is the same issue as katharostech/docker-plugin_lizardfs#8

[jadolg]

I was doing some experiments and looks like the way it works will make it hard to even kill the lfsmount application. When I try to kill it after mount it says process already finished.

[zicklag]

That's a little confusing because the parent process of the zombie should be the Docker plugin process, because that is the process that spawned it. I don't know why the container exiting causes the process to defuct. I could see there being a problem if the plugin container exited and left those processes around.

🤔

I wonder, maybe you could try running the container that is mounting a volume with the --init flag. This will run the tini init system to start the container and reap zombie processes, but still don't think that will work because the zombie was not a child of the container, it was a child of the plugin. Still it's worth a shot.

[jadolg]

I think I have an idea of what's happening but I'm not completely sure. I think lsfmount is forking itself upon execution and after this point, my application does not know about this process but the system does, so when it dies my application never processes the result and it stays there forever.
My current approach is to try to remove all zombies at some point and I have advanced a bit with this lib https://github.com/ramr/go-reaper
I can already see no defunct processes but now this new dependency is messing the replication goal setting as it kills the process before it's done.
I'll keep you updated.

[zicklag]

Oh, sweet. Looks like you're making progress. Awesome. 👍