Re: [ldm-users] LDM and systemd(8) 219

• To: Steven Emmerson <emmerson@xxxxxxxx>, LDM <ldm-users@xxxxxxxxxxxxxxxx>
• Subject: Re: [ldm-users] LDM and systemd(8) 219
• From: "Herzmann, Daryl E [AGRON]" <akrherz@xxxxxxxxxxx>
• Date: Sat, 28 Jan 2023 22:45:19 +0000
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Hi Steve,

Is this issue against systemd version 219 or version 219 and later or ?  
Version 219 of systemd is from 2015!?!

https://github.com/systemd/systemd/releases/tag/v219

daryl

________________________________________
From: ldm-users <ldm-users-bounces@xxxxxxxxxxxxxxxx> on behalf of Steven 
Emmerson <emmerson@xxxxxxxx>
Sent: Saturday, January 28, 2023 3:49 PM
To: LDM
Subject: [ldm-users] LDM and systemd(8) 219

Hello LDMer,

This email is to make you aware of an issue with the LDM on systems running 
version 219 of the daemon systemd(8). If you don't run systemd(8), then you may 
ignore this email until you do.

Version 219 of systemd(8) -- depending on how it was compiled for your 
operating system -- can, by default, cause all upstream LDM processes feeding 
downstream LDM processes to terminate due to an error. The downstream LDM 
processes will reconnect and this process will repeat indefinitely. This 
behavior is revealed by searching the upstream LDM's log file for the string 
"uldb.c". For example

$ fgrep uldb.c ~/var/logs/ldmd.log | head -2
20230111T183527.886480Z xxx.xxx.xxx(feed)[73820] uldb.c:db_lock:1742 ERROR 
Couldn't lock database for writing
20230111T183527.886488Z xxx.xxx.xxx(feed)[73820] uldb.c:uldb_addProcess:2152 
ERROR Couldn't lock database
$

This problem results from the LDM using a shared-memory segment to hold its 
list of active upstream LDM processes and systemd(8) deleting all of a user's 
inter-process communication objects (which includes shared-memory segments) 
when the user exits any session -- including ones launched via a crontab(1) 
entry!

Don't get me started on what I think about this behavior.

The solution is to stop systemd(8) from doing this by ensuring that the 
parameter "RemoveIPC" is set to "no" in the file "/etc/systemd/logind.conf":

# grep IPC -i /etc/systemd/logind.conf
#RemoveIPC=yes

If the value is "no", then nothing need be done, even if it's commented-out; 
otherwise, set its value to "no", make sure it's not commented-out, execute the 
command

systemctl restart systemd-logind

and then restart your LDM.

You can read more on this issue in the rant https://knzl.at/systemd-removeipc/ 
or by googling "systemd RemoveIPC".

Contact support-ldm@xxxxxxxxxxxxxxxx<mailto:support-ldm@xxxxxxxxxxxxxxxx> if 
you have any questions.

Regards,
Steve Emmerson

• Follow-Ups:
  • Re: [ldm-users] LDM and systemd(8) 219
    • From: Steven Emmerson

• References:
  • [ldm-users] LDM and systemd(8) 219
    • From: Steven Emmerson