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Topic: s6-log does not seem to exit (Read 715 times) previous topic - next topic
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s6-log does not seem to exit

When I run
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dbus-run-session sway |& s6-log -b -- n3 s2000000 T ~/.var/log/sway
in tty1 and exit sway via
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swaymsg exit
, the s6-log process for logging the sway program doesn’t seem to exit, while dbus-run-session has exited, though (I checked that via another tty). Does somebody have an idea why s6-log doesn’t exit?

Re: s6-log does not seem to exit

Reply #1 –
>Does somebody have an idea why s6-log doesn’t exit?

The binary itself or why it isn't started in the pipe process?

Re: s6-log does not seem to exit

Reply #2 –
s6-log the binary itself.
Quote
why it isn't started in the pipe process?
s6-log does start for me, I can see log contents in ~/.var/log/sway/current

Re: s6-log does not seem to exit

Reply #3 –
I'm guessing it's due to processes spawned by sway being kept alive after it closes. s6-log's stdin might be still connected to their stdout/err.

For example, this s6-log invocation will hang the terminal for 6 seconds despite the background command exiting immediately and the shell not being aware of the spawned sleep command (you can confirm with pstree):

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background -d -- sleep 6 "" | s6-log ~/.var/test


Also, are you sure sway's s6-log is the one hanging? There's multitude of s6-log's in any s6 system, and if your tty shows a prompt after exiting sway, it's likely not sway's logger.

Re: s6-log does not seem to exit

Reply #4 –
Quote
Also, are you sure sway's s6-log is the one hanging? There's multitude of s6-log's in any s6 system, and if your tty shows a prompt after exiting sway, it's likely not sway's logger.
Yes. I couldn’t see a prompt after exiting sway.

Quote
I'm guessing it's due to processes spawned by sway being kept alive after it closes. s6-log's stdin might be still connected to their stdout/err.
Ohhh, I wasn’t really aware that this is how it works, though it sounds logical. TIL. Also, this was the root of the issue, so thanks! I just fixed it and now everything works fine. Also thanks for the example!

Re: s6-log does not seem to exit

Reply #5 –
>I'm guessing it's due to processes spawned by sway being kept alive after it closes.

The process itself or their file descriptors?

Re: s6-log does not seem to exit

Reply #6 –
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The process itself or their file descriptors?
In my case  it was both, I guess. Processes were being kept alive, and therefore also their file descriptors.
 

Re: s6-log does not seem to exit

Reply #7 –
Quote from: Lancia – on
>I'm guessing it's due to processes spawned by sway being kept alive after it closes.

The process itself or their file descriptors?

The file descriptors. Mentioning just the processes was an oversimplification, but it hints at the most likely solution.

Technically you can have the processes close/redirect the stderr and stdout (so s6-log's lifetime doesn't depend on theirs anymore) or send the fd's via sockets to processes sway didn't spawn, but that's something very few do.