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20040917: Possible pqact issue in LDM?

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  • Subject: 20040917: Possible pqact issue in LDM?
  • Date: Fri, 17 Sep 2004 11:28:10 -0600
Steven,

>Date: Fri, 17 Sep 2004 11:50:51 -0500
>From: "Steven Danz" <address@hidden>
>Organization: Aviation Weather Center
>To: Steve Emmerson <address@hidden>
>Subject: Re: 20040913: Possible pqact issue in LDM?
> Keywords: 200409142045.i8EKjBnJ016694 LDM-6 ldmadmin pqact.conf

The above message contained the following:

> Hello again, had another thought/question on the queue and its 
> interaction with pqact.  I noticed the some of the
> changes in the pq.c assume that the offsets are ordered.... but are 
> they?

The changes to the pq(3) module have removed that assumption.  If that's
not the case, then you're using a wrong version of the pq(3) module.

> I seem to remember that the slots in
> the queue are reused, so couldn't the offsets get out of order if the 
> next available slot is at an offset lower
> than the last product inserted?

That is the working hypothesis.  The behavior of pqact(1) on your system
should verify or contradict it.

> Wasn't sure if the list of available 
> slots is always kept sorted in offset order.

It's not.

> Even if they were, could a product be inserted, a slot at a lower offset 
> freed up, then a second product inserted
> with an identical timestep to the first?  Not sure if a n-way system 
> could cause that scenario or if a machine
> could be fast enough on its own to do that.
> 
> Just another thought...   things are still looking good with the 6.1.1.1!

Keep me posted.

> Thanks again!
> 
> Steven
> -- 
> Senior Software Development Engineer
> Aviation Weather Center (NOAA/NWS/NCEP)
> 7220 NW 101st Terrace, Room 101
> Kansas City, MO 64153-2371
> 
> Email: address@hidden
> Phone: 816.584.7251
> Fax:   816.880.0650
> URL:   http://aviationweather.gov/

Regards,
Steve Emmerson