Crontab run-parts

Question

I am looking at run-parts script on CentOS 7. Very similar to this:

https://github.com/ikysil/run-parts/blob/master/run-parts

It appears to run everything in the cron.hourly etc. directories in sequence with a random delay between 1 and 300 seconds.

I have a lot of scripts in cron.hourly I must run for my unique setup. What I would like is all of them run at same time but with random delay before each.

Something like:

directory_script_list = contents(/etc/cron.hourly)
for script in directory_script_list:
  if script_is_executeable(script):
    execute(sleep(random(1, 300)) && script) &)

I do not want the server swamped every hour when they hit and I also do not want one of these scripts blocking the others.

The scripts do not use much CPU load what they mostly do is query slow replying SNMP devices, lots of them and in lots of ways. Some take a long time to complete and some are very quick. Not a lot of network traffic either. There are currently about 30 scripts but I frequently add, update and remove them.

Does anyone know of something that exists like this?

Answer 1

Since run-parts is very close to what you want, you could make a copy of run-parts and modify it to make it exactly what you want.

For instance:

# cp -a /usr/bin/run-parts /usr/local/bin/run-parts-parallel

Then add an '&' after the last 'fi' in /usr/local/bin/run-parts-parallel, as you can see in this diff:

# diff -u /usr/bin/run-parts /usr/local/bin/run-parts-parallel 
--- /usr/bin/run-parts  2014-06-09 18:14:31.000000000 -0400
+++ /usr/local/bin/run-parts-parallel   2017-02-03 14:55:11.327000000 -0500
@@ -95,7 +95,7 @@
               { print; }'
        logger -i -p cron.notice -t "run-parts($1)" "finished $(basename $i)"
    fi
-   fi
+   fi &
 done

 exit 0

You can then change the line in /etc/cron.d/0hourly from:

01 * * * * root run-parts /etc/cron.hourly

to

01 * * * * root RANDOMIZE=1 RANDOMTIME=300 /usr/local/run-parts-parallel /etc/cron.hourly

The script could also be modified to use /etc/sysconfig/run-parts-parallel to set the RANDOM* variables and remove them from the crontab file. Or, if you're not using run-parts elsewhere, you can put the RANDOM* variables in /etc/sysconfig/run-parts to make the random delay the global default.