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TOPIC: another instance of YACReaderLibrary is running

another instance of YACReaderLibrary is running 2 months 3 weeks ago #6126

Joe

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Hi there,

I'm running YACReaderLibrary 9.6.2 on a Debian Stretch without any issue so far.

Recently, I was not able to load the server. Here is the error message :
YACReaderLibraryServer start

INFO  2021-07-06T11:11:19.204 YACReaderLibraryServer attempting to start
INFO  2021-07-06T11:11:19.204 ---------- System & configuration ----------
INFO  2021-07-06T11:11:19.204 OS: "Debian GNU/Linux 9 (stretch)" Version:  "9"
INFO  2021-07-06T11:11:19.204 Kernel: "linux" "4.9.0-8-amd64" Architecture: "x86_64"
INFO  2021-07-06T11:11:19.204 Libraries:  QMap((**)))
INFO  2021-07-06T11:11:19.204 --------------------------------------------
WARN  2021-07-06T11:11:19.204 another instance of YACReaderLibrary is running

It seems that I have two processes running, but all i found are defunct processes so I cannot kill anything :
ps x | grep YAC
12616 ?        Zl     4:19 [YACReaderLibrar] <defunct>
25055 ?        Zl     0:07 [YACReaderLibrar] <defunct>
32743 pts/3    S+     0:00 grep YAC

Do you if there is something I should do in order to restart the restart ?

Regards,

Jo
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another instance of YACReaderLibrary is running 2 months 3 weeks ago #6127

selmf

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These are zombie processes. They are already dead, so you can't kill them, but their parent process is still waiting for them. You can either reboot the system, manually alert the parent process or kill the parent process to clean them out.

I'd recommend reading a bit on the topic. This Wikipedia entry is a good start: en.wikipedia.org/wiki/Zombie_process
My answers are not necessarily official YACReader statements but mostly represent my own opinion in technical matters.
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another instance of YACReaderLibrary is running 2 months 3 weeks ago #6128

Joe

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Hey selmf,

Thanks for the quick answer.

Actually, I figured out it was zombie process but I fail to guess what the master process is, provided I launched YACLibraryServer manually into a tmux window. Isn't the defunct process supposed to be killed with the window ?

Just trying to figure out what happened here, as I will probably just reboot as you proposed.

Much regards,

Joe
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another instance of YACReaderLibrary is running 2 months 3 weeks ago #6129

selmf

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Thank you received: 130

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A zombie process is already killed and is just waiting for its parent process to check its exit status to be removed from the process list. So what happened here is probably that you closed the tmux window without stopping the library server first. This killed the server, but as its parent, the tmux session, could no longer check this it became a zombie process (or possibly an orphan process). The server checks for itself to be present in the process list, so it wont start in this case.

You can avoid it by pressing Ctrl+C to exit YACReaderLibraryServer or kill it by other means before closing the window.

If you don't want to reboot, finding a way to identify the parent process and resolving the zombie situation is just a short web search away :)
My answers are not necessarily official YACReader statements but mostly represent my own opinion in technical matters.
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another instance of YACReaderLibrary is running 2 months 3 weeks ago #6130

Joe

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Oh i see ! I will check this out. Zombies and orphans will be slashed tonight :evil:
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