[collectd] Not sleeping because `timeval_sub_timespec' returned non-zero! Causing? -- No data every so often

[Florian Forster]

Hi Simon,

On Tue, Mar 13, 2007 at 02:35:32PM -0000, Atack Simon wrote:
> In a 15 minutes period  I see " Not sleeping because
> `timeval_sub_timespec' returned non-zero! " in syslog from collectd 4
> or 5 times and no updates on the graphs [ they are blank for this
> reading ].  What is causing this and what can I do to fix the issue?

collectd collects it's data every 10 seconds. Reading of all values
takes some time and after that the daemon sleeps for `10-<time>'
seconds. If `<time>' is greater than 10 (i. e. it took more than 10
seconds to get values from all plugins) it will not sleep (for a
negative amount of seconds) but query the plugins again right away.

Since the main daemon itself does hardly anything this is most likely
caused by a plugin, likely one that does some network-IO. Try the
following:
- Disable all plugins you don't use. If that solves the problem: Great.
- Try disabling network-based plugins. These are `apache', `apcups',
  `hddtemp', `mbmon', `mysql' and `ntpd'. If one of them is causing the
  trouble, it's likely not configured and waiting for some timeout.
- Do you have plugins configured to do `real' network connections, such
  as the apache-plugin not querying `localhost'? (The ping-plugin
  doesn't count, obviously ;) The network-latency may cause the problem,
  too. Try installing `collectd' on the target machines and let them run
  in `client mode'.

Please let me know about your findings so I can update the `FAQ'-page on
the homepage, since this question has come up before..

Regards,
-octo
-- 
Florian octo Forster
Hacker in training
GnuPG: 0x91523C3D
http://verplant.org/
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