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Old 07-23-2007, 04:49 AM   #1
TrAvIkK
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Cron / second precision ?


Hi there!

I'm wondering - CRON entry allows to set up a cron job with minutes, hours, days etc.
But what if i need to do something at 6:23:38 ? I mean, i need second precision?
 
Old 07-23-2007, 05:10 AM   #2
rupertwh
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Quote:
Originally Posted by TrAvIkK
But what if i need to do something at 6:23:38 ?
I don't know if cron can be relied upon to always start jobs at the full minute. If it can, then adding your job as
Code:
23 6 * * * sleep 38 && myjob
should do the trick.
 
Old 07-23-2007, 05:16 AM   #3
TrAvIkK
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Yeah, but sleep 38 means processor usage by 38 sec?
If yes, that is not the answer i was expecting on. I need to take carve about processor usage.
 
Old 07-23-2007, 05:56 AM   #4
slakmagik
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Quote:
Originally Posted by rupertwh
I don't know if cron can be relied upon to always start jobs at the full minute.
My cron jobs always start after the minute, and not precisely - at least 9 out of 10 times it's :01, with the rest being :02. I wouldn't be surprised if on a more heavily loaded system it would vary more and sometimes run later.

Quote:
Originally Posted by TrAvIkK
Yeah, but sleep 38 means processor usage by 38 sec?
Sleep uses no (or virtually no) CPU.

/me wonders what cron job could require second precision, though.
 
Old 07-23-2007, 06:20 AM   #5
TrAvIkK
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Hmm what job?
Well, i'm a developer of Web-Based MMO, and some operation (as Battle calculations etc.), which calculating them by users interaction would take too much time.
 
Old 07-23-2007, 02:10 PM   #6
Matir
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Cron is not intended for high-accuracy timing. It CAN be and is frequently off by several seconds (due to process start-up, etc.). If you need that kind of precision, I suggest running a daemon of your own to avoid process start-up overhead.
 
Old 07-23-2007, 03:15 PM   #7
TrAvIkK
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Quote:
Originally Posted by Matir
Cron is not intended for high-accuracy timing. It CAN be and is frequently off by several seconds (due to process start-up, etc.). If you need that kind of precision, I suggest running a daemon of your own to avoid process start-up overhead.

How to do such thing?
Coz I think i like it

I mean, i know I have to write it by my own (well, as for now - i'm onyl learning C++, so it could be kind of hard :P), but may be there are on internet some examples?

Last edited by TrAvIkK; 07-23-2007 at 03:24 PM.
 
Old 07-23-2007, 03:25 PM   #8
Matir
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Write a daemon (basically any continuously-running application) that handles the updates you need.

http://www.google.com/search?q=daemo...ient=firefox-a
 
Old 07-23-2007, 04:08 PM   #9
TrAvIkK
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Quote:
daemonize();
while(1) sleep(1); /* run */
Well, so that is the continously handler ^^
 
  


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