IOMonitor Plugin does not use optimal /proc parameter to find process PID

One more piece of useful information. Processes without a /proc/PID/cmdline can be easily identified in the ps list, in that they have their process names placed inside square brackets. From the ps man page:

       args COMMANDcommand with all its arguments as a string. Modifications to the arguments may be shown. The output in this column may contain spaces. A process marked <defunct> is partly dead, waiting to be fully destroyed by its parent. Sometimes the process args will be unavailable; when this happens, ps will instead print the executable name in brackets.

It occurred to me just after writing this bug report, that some people may be using the current functionality of the regex search of the cmdline to find a particular instance of a process based on its args.

So a better enhancement idea may be to keep the current functionality of scanning the /proc/PID/cmdline with the regex expression while adding a second regex search of the Name: field in the /proc/PID/status file using the same expression. Then monitor the PID if either of the two searches successfully finds a match using the regex search (a logical OR of the two searches, with only one match required to declare the PID monitored)

This would preserve existing functionality of allowing a more specific search of the cmdline (with arguments), should the use specify a more complex regex that will match specifically a given cmdline for a particular process. It would also now enable the monitoring of a set of processes that lack a cmdline (such as NFSD) if the user specifies just the process name for the regex search, which will be found by the search of the Name: field in the status file.

Hi there,

Thank you for reporting bugs and trying to make Ubuntu better.

I'll take a look at this later this week however, after a quick look /proc/<PID>/status I found that under the field name, some processes names that are long might not show the complete name, i.e.:

$ cat status
Name: chromium-browse

Note that the complete name of the process is not shown when it should. This might affect regex's for daemons which name's too long. In turn, cmdline shows:

$ cat cmdline
/usr/lib/chromium-browser/chromium-browser --type=extension --lang=en-US --force-fieldtest=ConnCountImpact/conn_count_8/ConnnectBackupJobs/ConnectBackupJobsEnabled/DnsImpact/max_2s_queue_prefetch/DnsParallelism/parallel_14/GlobalSdch/global_enable_sdch/IdleSktToImpact/idle_timeout_60/Prefetch/ContentPrefetchDisabled/ProxyConnectionImpact/proxy_connections_32/SpdyCwnd/cwnd16/SpdyImpact/npn_with_spdy/ --channel=4516.0x7f839042d000.717038638

Cheers,

Indeed,

That's what I was thinking about too. Since this would be considered as a bug it would make it to natty in case it's decided to go thru with this.

Cheers!

This bug was fixed in the package powernap - 2.6-0ubuntu1

---------------
powernap (2.6-0ubuntu1) natty; urgency=low

  * debian/copyright: Update upstream authors and license years.
  * powernap/monitors/IOMonitor.py: If processes do not have a command line,
    search regex in the 'Name:' field of /proc/<PID>/status (LP: #735452)
  * actions/cpu_frequency: Fix saving/restoring of wrong governor (LP: #743682)
    Thanks to Mathieu Berard for the patch.
    - Additionally, save 'ondemand' as default when acpi-support and ondemand
      are run on boot to handle special case when running on battery.
  * debian/powernap.{preinst,postinst}: Add logic to handle the upgrade of
    the config file as format has changed. (LP: #744588)
    - install copy of config file in /usr/share/powernap to help with this.
 -- Andres Rodriguez <email address hidden> Mon, 28 Mar 2011 17:38:34 -0400