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Archie5000

Member

Registered: 2015-05-10

Posts: 7

Does systemd kill my program because it found error messages in log?

Hi,

I have a small program that does not fork.
I start this program via systemd:

[Unit]
Description=jobqueue

[Service]
ExecStart=/home/jobq1
Restart=always
RestartSec=5
WorkingDirectory=/home
Type=simple

[Install]
WantedBy=multi-user.target

My program talks to a usb device.
My problem is: As soon as I disconnect the USB from the computer, my jobqueue program terminates.
I think systemd scans the logfiles because I find there a expectable ftdi error that complains about the USB disconnect. This log-entry is in red color.

jobq1 kernel: ftdi_sio ttyUSB0: usb_serial_generic_read_bulk_callback - urb stopped: -32

Running my program on the console by hand does not exit when I disconnect the USB-cable. My program is prepared of usb disconnects.

So I suspect systemd is killing my program because it thinks it has found a problem found in the logfile.

How can I stop this behavior?

Thank you!

Archie

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 20,334

Re: Does systemd kill my program because it found error messages in log?

No, it does not scan the log looking for errors as a precursor to killing things.

Edit:  Your service file looks reasonable, I would expect it to restart after 5 seconds.   Are you running this at the user level or the system level ?  How about when you run it by hand?  What are the owner, group and permissions on the device node of the USB device?  Are there any files in /home that are needed by the process? who owns them?

Edit2:  Can you share the program?

Last edited by ewaller (2016-10-20 22:56:36)

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Archie5000

Member

Registered: 2015-05-10

Posts: 7

Re: Does systemd kill my program because it found error messages in log?

Thank you for your answer.

I think it might have to do with KillUserProcesses=yes and systemd thinks the USB-unplug is a user-disconnect?

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 20,334

Re: Does systemd kill my program because it found error messages in log?

Seems reasonable.  You should experiment with that.

---

Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

Archie5000

Member

Registered: 2015-05-10

Posts: 7

Re: Does systemd kill my program because it found error messages in log?

Sorry, just answered, did not read your edited text. The thing is that on a ps aux the tty is "?", when I plug the usb in it is suddenly ttyUSB0 and I think the unplug kills it then. But  KillUserProcesses=no (plus reboot to be sure) in logind.conf doesn't help. Is there a way to assign the program another tty before so it does not look for ttyUSB0?

Edit: Running by hand works flawless, jobqueue runs as root, jobq-service is in /etc/systemd/system dir.

Last edited by Archie5000 (2016-10-20 23:32:32)

Archie5000

Member

Registered: 2015-05-10

Posts: 7

Re: Does systemd kill my program because it found error messages in log?

It definitively has to do with systemd because when I start the program using systemd with setsid so that the jobqueue-program loses its status as being a process "descendant", then the program continues to run, becuase systemd is no longer aware that the program is the one to check permanently.