Munin: Graphs for Processes priority are empty

Question

I have a new Ubuntu server (Ubuntu 16.04.1 LTS, server version without GUI, running as a virtual server in a remote server farm), and I installed munin on it (munin and munin-node). I did not change anything from the standard installation, so at the moment I use the 30 plugins that are part of the standard installation. 28 of them worked fine from the beginning.

The plugin "HTTP load time of a page" showed an empty graph, but I found out that the package time was missing. I installed it with

apt install time

and restarted munin-node. So now this plugin is fixed.

But there still is a problem with »processes priority« (plugin »proc_pri«). The graphs of this plugin (by day, by week, ...) are all empty, and I have now idea where I could start to search for the reason of this problem.

Please can you give me some hints what I could do to fix this problem? Or what I could do to isolate the problem.

Answer 1

Check the output of ps -eo stat command. Munin plugin proc_pri is the simple shell script that process output of ps and may fail after output format changing. UPD: It simply count lines with symbols ">", "N" and "L" in the ps -eo stat command output. Therefore if this command dont show full list of processes or use non-BSD output format, plugin will not count processes correctly.