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I have a cron task as

6,36 * * * * python /usr/local/news.py >> /var/log/newlog

it is supposed to run at every 6th and 36th minute of each hour.

But for some how the system runs this task 4 processes/times each time. This task is to update database, and it causes problem when three processes updating database at the same time.

I have 4 tasks listing in /var/spool/cron/root, this is one of the tasks

What possibly went wrong here?

Thanks

Edit:

Oct 9 20:06:01 online CROND[7882]: (root) CMD (python /usr/local/news.py >> /var/log/newslog)  
Oct 9 20:06:01 online CROND[7883]: (root) CMD (python /usr/local/news.py >> /var/log/newslog)  
Oct 9 20:06:01 online CROND[7888]: (root) CMD (python /usr/local/news.py >> /var/log//newslog)  
Oct 9 20:06:01 online CROND[7890]: (root) CMD (python /usr/local/news.py >> /var/log//newslog)
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  • What does your log say?
    – Dennis Williamson
    Oct 10, 2009 at 2:02
  • I mean /var/log/cron.log rather than the one in the crontab line above.
    – Dennis Williamson
    Oct 10, 2009 at 2:04
  • Oct 9 20:06:01 online CROND[7882]: (root) CMD (python /usr/local/news.py >> /var/log/newslog) Oct 9 20:06:01 online CROND[7883]: (root) CMD (python /usr/local/news.py >> /var/log/newslog) Oct 9 20:06:01 online CROND[7888]: (root) CMD (python /usr/local/news.py >> /var/log//newslog) Oct 9 20:06:01 online CROND[7890]: (root) CMD (python /usr/local/news.py >> /var/log//newslog)
    – Weiwei
    Oct 10, 2009 at 3:28
  • 4 lines of "Oct 9 20:06:01 online CROND[7890]: (root) CMD (python /usr/local/news.py >> /var/log//newslog)" running at the same time, now sure what is going on
    – Weiwei
    Oct 10, 2009 at 3:29
  • FYI: I have 4 tasks listing in /var/spool/cron/root
    – Weiwei
    Oct 10, 2009 at 3:49

3 Answers 3

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What is the result of the following command? If there is more than one number listed then cron is running more than once which could cause this problem.

pgrep -l cron
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  • 3674 crond 6335 crond 20785 crond 22084 crond
    – Weiwei
    Oct 10, 2009 at 14:27
  • i have this output when i run pgrep -l cron " 3674 crond 6335 crond 20785 crond 22084 crond " It looks i have 4 copies of crond are running at the same time?
    – Weiwei
    Oct 10, 2009 at 14:30
  • Thanks! i think problem should be gone (after i rebooted my server). For somehow I have 4 instances of crond running at the same time.
    – Weiwei
    Oct 10, 2009 at 14:41
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By 'I have 4 tasks listing in /var/spool/cron/root', do you mean:

'I have 4 lines in root's crontab, all the same thing.'?

Please paste the output of 'crontab -l'. If it looks anything like:

6,36 * * * * python /usr/local/news.py >> /var/log/newlog
6,36 * * * * python /usr/local/news.py >> /var/log/newlog
6,36 * * * * python /usr/local/news.py >> /var/log/newlog
6,36 * * * * python /usr/local/news.py >> /var/log/newlog

That's definitely the problem :0

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2
  • sorry, no i have for different tasks. the one 6,36 * * * * python /usr/local/news.py >> /var/log/newlog is only one of them
    – Weiwei
    Oct 10, 2009 at 4:15
  • In that case, you don't happen to have started 4 instances of crond somehow, have you? Is this the only task that runs 4 copies at the same time, or do all tasks do so? Also, please paste the output of 'crontab -l' into your question.
    – MikeyB
    Oct 10, 2009 at 4:23
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It looks like two of the runs have a slightly different syntax. Could you check /etc/crontab and /etc/cron.d to check you don't have copies of the command there?

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