cron task problem

Question

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)

I mean /var/log/cron.log rather than the one in the crontab line above. — Dennis Williamson, Oct 10 '09 at 02:04
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 '09 at 03:28
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 '09 at 03:29
You should post follow-ups with listings like that as an edit of your answer. Then you can use quote block formatting to make it more readable. I'll take care of it for you. — Dennis Williamson, Oct 10 '09 at 04:21
Please take a few minutes to correct your many typos - your mistakes are making assisting you difficult. For example, according to the lines from syslog that you pasted, you have two similar but different commands running. — MikeyB, Oct 10 '09 at 04:34

score 1 · Answer 1 · answered Oct 10 '09 at 04:14

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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

answered Oct 10 '09 at 04:14

MikeyB

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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 '09 at 04:15
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 '09 at 04:23

score 1 · Accepted Answer · answered Oct 10 '09 at 08:13

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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

answered Oct 10 '09 at 08:13

emills

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3674 crond 6335 crond 20785 crond 22084 crond – Weiwei Oct 10 '09 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 '09 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 '09 at 14:41

score 1 · Answer 3 · answered Oct 10 '09 at 08:58

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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?

answered Oct 10 '09 at 08:58

Douglas Leeder

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cron task problem

3 Answers3