FW: Problem with initial service scheduling (2.0b3)

[Andreas Ericsson]

François Laupretre wrote:
> Sorry for posting this message again but I cannot modify my production
> environment before having an opinion from somebody who understands the
> 'interleave_block' stuff.
> 

I think Ethan's the only one who really does.

Here's the doco for it though.
http://nagios.sourceforge.net/docs/2_0/checkscheduling.html#service_interleaving

As for the algorithm, I believe
max_service_check_spread * (total_active_services / 
total_scheduled_services)
is more proper.


> Thanks in advance
> 
> 
>>-----Original Message-----
>>From: Laupretre, François (CALYON) 
>>Sent: Thursday, June 09, 2005 2:56 PM
>>To: nagios-devel at lists.sourceforge.net
>>Subject: Problem with initial service scheduling (2.0b3)
>>
>>
>>Hi all,
>>
>>I currently have a configuration with 4800 services : 600 
>>active and 4200 passive. And, as the number was growing, I 
>>noticed a problem in the way nagios scheduled their initial 
>>check time : With the 2.0b3 original code, with 
>>max_service_check_spread=30, when I look at the scheduling 
>>queue just after start, I see that the last service checks 
>>are scheduled to run in 4 hours !
>>
>>This delay corresponds to :
>>
>>max_service_check_spread * (total_services / total_scheduled_services)
>>
>>And should be equal to max_service_check_spread.
>>
>>I found the reason in event.c/init_timing_loop() and I am 
>>including a change which appears to correct the problem but, 
>>as I am not sure to fully understand the 'interleave_block' 
>>logic, this change should be taken with care :
>>
>>The reason : in the 'schedule service checks' section of 
>>init_timing_loop(), next check time is incremented for each 
>>service, and not for each SCHEDULED service. So, in my case 
>>it is incremented 'total_services' times and the last check 
>>time is equal to :
>>
>>Current_time + total_services * service_inter_check_delay
>>
>>Where it should be :
>>
>>Current_time + total_scheduled_services * service_inter_check_delay
>>
>>Which is coherent with the way service_inter_check_delay is computed.
>>
>>My change consists of taking the 'should_be_scheduled' check 
>>out of the inner loop, and add a line in order to have the 
>>code enter the inner 'interleave_block' loop only for active 
>>checks. This way current_interleave_block goes from 0 to 
>>total_schedules_services instead of going up to total_services.
>>
>>Once again, the patch I am submitting seems to correct the 
>>problem in MY case. But I don't know if it is correct when 
>>interleave variables have some different values.
>>
>>Regards
>>
>>François
>>
> 
> 
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-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Lead Developer


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