Multiple (thousands) of Cron Instances


 
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# 1  
Old 12-30-2005
Multiple (thousands) of Cron Instances

Hey all,

I have a box running SUSE SLES 8 and in the past few months the box will randomly spawn thousands of instances of /USR/SBIN/CRON to the point where the box will lock up entirely. Upwards of 14000 instances! I imagine it's using up all of the available files that can be opened at one time and hanging the box. It seems to happen every few months.

It's running Vixie cron, but the odd thing is I have 11 other boxes running the same OS, the same exact build and the same exact crontab and none of them are doing this.

Does anyone any experience with this happening?

Thanks.

-Sys
# 2  
Old 01-03-2006
Quote:
Originally Posted by sysera
Hey all,

I have a box running SUSE SLES 8 and in the past few months the box will randomly spawn thousands of instances of /USR/SBIN/CRON to the point where the box will lock up entirely. Upwards of 14000 instances! I imagine it's using up all of the available files that can be opened at one time and hanging the box. It seems to happen every few months.

It's running Vixie cron, but the odd thing is I have 11 other boxes running the same OS, the same exact build and the same exact crontab and none of them are doing this.

Does anyone any experience with this happening?

Thanks.

-Sys
Just a little bump to see if anyone has any ideas on this. I've yet to find any information on it. I assume many people were on holiday this past week when I posted this. Thanks guys. Smilie
# 3  
Old 01-04-2006
I encounter this on RedHat as well.
I noted some of the system files permission got messed up.
In the end I reinstall the OS.
Fortunately, it is a lab server.
# 4  
Old 01-04-2006
Quote:
Originally Posted by izy100
I encounter this on RedHat as well.
I noted some of the system files permission got messed up.
In the end I reinstall the OS.
Fortunately, it is a lab server.
Fortunately for me too it is only a testing system, but the fact that I've had no luck getting to the root cause is a bit frightening. Smilie
# 5  
Old 01-04-2006
have you tried comparing the checksums of the cron binaries across the similar systems?
# 6  
Old 01-04-2006
Quote:
Originally Posted by Just Ice
have you tried comparing the checksums of the cron binaries across the similar systems?
No I have not, this is an excellent idea. I'll make sure I do this first thing tommorow. Thank you. Smilie
# 7  
Old 01-05-2006
Just one thing, when a cronjob is executed, cron forks itself and execs the job under that process. So if you have thousands of cronjobs scheduled very close together, you may see thousands of cron processes.

The next time you see such behaviour, check the ppid of all the cron processes. If it is the same, they were spawned from the cron daemon.
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