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Full Discussion: Kind of knapsack problem
Top Forums Shell Programming and Scripting Kind of knapsack problem Post 302144306 by ngungo on Wednesday 7th of November 2007 08:41:54 AM
Old 11-07-2007
Kind of knapsack problem

I need to run as many (thousands) very small cron jobs within a duration of 5 minutes and repeatedly through out the day. This kind of requirement would be up against system resources and limitations such as nproc, maxuprc, numbers of cron jobs allowed in crontab, RSS, SWAP, CPU and others that I don't know. The problem is typical knapsack problem, maximize number of jobs within constrains.

1. A typical cron job is to monitor responsiveness of a webpage. A simplified one-liner would be: time -p wget http://domain.com where domain.com is varied.

2. I have root access

3. At the other thread I read the below script, what is the purpose of the wait command? Can I use the above one-liner as a job in this example?
Quote:
#! /usr/bin/ksh
job1 &
job2 &
job3 &
wait
exit 0
4. In general, what do I have to do? What strategy?

Thanks in advance, your advise appreciated.
 

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CRONTABS(4)						      Crontabs users' Manual						       CRONTABS(4)

NAME
crontabs - configuration and scripts for running periodical jobs SYNOPSIS
run-parts [--list|--test]<directory> DESCRIPTION
Crontabs is a historical name for the run-parts script and the system crontab. The run-parts script runs all executables in the specified directory. Run-parts runs all executables in the specified directory. The execution of files can be allowed or denied by creating file jobs.allow or jobs.deny which worked similar as other allow/deny config files. The file must be created in the specified directory. --list print names of all files (not limited to executables), but don't run them. This option can't be used with test option. --test print names of files, which would be run. Randomization of jobs can be configured in the /etc/sysconfig/run-parts file. To enable randomization of jobs, set the RANDOMIZE parameter to 1 and set the RANDOM parameter to an integer which determines a random seed. Additionally, you may configure the RAN- DOMTIME parameter (again, by specifying an integer) to provide an additional level of randomization. Jobs are not randomized when the RANDOM and RANDOMTIME parameters are set to 0. Values in these two parameters must be set to 1 or larger to provide a good enough randomization. Randomization of cron jobs can be useful for shared networks, where multiple cron jobs executed at once can cause spikes in traffic, especially during daily jobs. With randomized jobs, the workload is evenly distributed throughout the day. EXAMPLE OF CONFIGURATION FILE
RANDOMIZE=1 RANDOM=4 RANDOMTIME=8 Historically the crontab file contained configuration which called run-parts on files in cron.{daily,weekly,monthly} directories. These jobs are now run indirectly through anacron to prevent conflicts between cron and anacron. That means the anacron package has to be installed if the jobs in these directories should be running. Refer to the anacron(8) how to limit the time of day of the job execution. EXAMPLE
/etc/cron.daily/jobs.deny could contain for example 0logwatch which forbid execution of this script. SEE ALSO
anacron(8), crontab(5) Marcela Malaova 2012-08-29 CRONTABS(4)
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