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[Bug 1429427] Re: Unexplainable time jumps in CRON

 

Hi Stefan,

yup yup, same here, only showing for cron related entries in syslog.
Also somewhat busy due to a noisy sogo/postfix/openchange/dovecot plus
all sorts of extra add-ons. Not nearly as noisy as a firewall logging of
course ;-)

Can you strace your cron pid for a bit, including forks and hopefully confirm it is sending correct dates to syslog?
Next you can try then is to strace your rsyslog, which will be very noisy so you best grep for cron related stuff only ;-)

Are you using rsyslog? And are you also seeing that xconsole noise?

After my rsyslog restart this morning, not seeing any time jumping for
cron in syslog just yet, so it's likely also related to something
happening over time, like a buffer or other memory related issue.

You could try the same, restart rsyslog and see how long it takes for
things to start jumping around again...

Cheers,

GJ

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https://bugs.launchpad.net/bugs/1429427

Title:
  Unexplainable time jumps in CRON

Status in rsyslog package in Ubuntu:
  Confirmed

Bug description:
  On my main server I see unexplainable time jumps backwards in the syslog. Those jumps affect CRON.
  Example:

  Feb 10 06:48:01 nostromo CRON[20351]: (root) CMD (    /storage/exec/checkinternet.sh 2>/dev/null 1>/dev/null)
  Feb 10 06:49:01 nostromo CRON[20364]: (root) CMD (    /storage/exec/checkinternet.sh 2>/dev/null 1>/dev/null)
  Feb 10 06:50:01 nostromo CRON[20386]: (root) CMD (    /storage/exec/status-nostromo.sh >/dev/null 2>&1)
  Feb  7 05:40:01 nostromo CRON[20389]: (root) CMD (    /storage/exec/checkinternet.sh 2>/dev/null 1>/dev/null)
  Feb 10 06:50:01 nostromo CRON[20390]: (root) CMD (    /storage/exec/checkinternet.sh 2>/dev/null 1>/dev/null)
  Feb 10 06:50:01 nostromo CRON[20391]: (root) CMD (    /storage/exec/checkip.sh 2>/dev/null 1>/dev/null)

  For debugging I did the following:
  Start xclock and watch xclock and tail -f /var/log/syslog in parallel. When CRON logged a wrong time, xclock did NOT show any time jump but seemed to freeze for a fraction of a second.
  Open a screen and start a script that will once per second read the time (in unix seconds) and compare the read time with the time read a second ago. If the current time was smaller, the script would send an email with a process list from before and after the jump. The script also never detected any time jump.

  In summary, my current impression is that there might be a bug in CRON because no other programm seems to be able to see the "wrong" time. The server in question is syslog server for 4 servers and 3 network devices. The time jumps exclusively show in syslog entries from the local CRON instance. Not in any remote syslog entry and not in any other local syslog entry, e.g. from DHCPD, bind, tftpd, etc. etc.
  Also, after a reboot, things work ok for several days upto about 2 or 3 weeks. Then the "time jumps" start to occur with increasing frequency.

  I don't use user crontabs but maintain all jobs in /etc/crontab. I
  have number of jobs which are triggered every minute and another
  number of jobs which are triggered every 5 minutes (maybe some CRON
  internal counter overflow problem?).

  Hardware:
  Asus P9D-V
  Intel Xeon E3-1240L V3
  16GB ECC RAM
  128GB SSD System
  3x3TB ZFS RaidZ2 storage
  1x3TB Misc. data

  CMOS battery already changed and board inspected.

  nostromo:~ # lsb_release -rd
  Description:    Ubuntu 14.04.2 LTS
  Release:        14.04

  nostromo:~ # apt-cache policy cron
  cron:
    Installed: 3.0pl1-124ubuntu2
    Candidate: 3.0pl1-124ubuntu2
    Version table:
   *** 3.0pl1-124ubuntu2 0
          500 http://us.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
          100 /var/lib/dpkg/status

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References