Applicable to:
- Plesk for Linux
Symptoms
High CPU usage for sa-learn and spamtrain processes in the server.
Cause
As sa-learn script is used by spamassassin to learn the specific properties of spam from a folder which supposedly contains only spam emails.
CPU usage of the sa-learn process depends on the amount of the emails in mailboxes and its size. Then if the number of emails is huge - CPU overusage is expected.
Resolution
To workaround the issue use one of the following solutions:
-
Connect to the server using SSH.
-
Use nice or ionice utilities to decrease the priority of
sa-updatefrom the cron tasks. -
Create a wrapper file which will execute
sa-learnwith the lowest CPU priority:# cp -a /usr/bin/sa-learn{,.orig}
# echo "/bin/nice -19 /usr/bin/perl -T -w /usr/bin/sa-learn.orig $@" > /usr/bin/sa-learn
# chmod +x /usr/bin/sa-learn -
Set the lowest priority to the currently running
sa-learnprocesses execute the following:# for i in $(ps axuwf | grep sa-learn | awk '{print $2}'); do renice 19 $i; done
Note: Process priority values range from -20 to 19. A process with the nice value of -20 is considered to be on top of the priority. And a process with nice value of 19 is considered to be low on the priority list.
-
Disable the
sa-updateexecution by moving60sa-updateandspamassassinfiles from/etc/cron.dailyto a different location:# mv /etc/cron.daily/60sa-update /root
Comments
2 comments
Are you sure that we need to modify 60sa-update in order to change high cpu from sa-learn?
This pstreelog output (C7, P17.8.x) would suggest otherwise:
|-anacron---run-parts-+-50plesk-daily---sw-engine---sw-engine---spamtrain---su---sa-learn
I couldnt find any mentioning of sa-learn in sa-update either. Please advise.
@Alexander Bien
Thank you for the feedback. The article has been updated.
Please sign in to leave a comment.