When to execute cron-tasks - Toolserver-l

13 Sep 2012

Hello all,

a few users contacted me about their not running cron-tasks. A often found 
problem is, that the cron-lines of these user are like the following:

0 0 * * * DoSomething

or 

0 * * * * DoSomething

In a ideal world that would be no problem, but in real world that CAN be a 
problem. Why? Because many users have the same idea and our submit-hosts fail 
than with 

(CRON) CAN'T FORK (child_process): Not enough space.

Last night 41 tasks were successful started at midnight, an unknown number 
failed.
Of course we could just hit the problem with buying new hardware, but most 
time of the day these hosts do idle.
So how to solve this problem? It's easy: Spread the load. Most times a task 
(like a bot) do not care if it is started a few minutes earlier or later. So 
choose a minute that is unlike 0 and not divisible without remainder by 5.
If it really does not matter for you when your task starts, then take the 
position of the first letter of your user-name and add 2 ("dab" → "d"
→ 4 → 6).
To not produce a misunderstanding: If your task REALLY needs to start at 
minute 0 (or at midnight): do it. An of course cron-tasks are failing for 
other reasons to, so contact me (jira-bug preferred) if you have a problem.

Sincerely,
DaB.

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