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20020108: Throughput of a product inserted into LDM and processed by pqact


>To: address@hidden
>From: Gregory Grosshans <address@hidden>
>Subject: Throughput of a product inserted into LDM and processed by pqact
>Organization: UCAR/Unidata
>Keywords: 200201081743.g08HhUN29882

Is there a way to determine how long a particular product  is in the LDM
system (i.e. once its inserted into the LDM queue until pqact has acted
on it)?

Thanks,
Gregg

---------------------------------------------------------------------

Gregg,

In LDM 5.1.4, the following was added:

                Added "Delay: x.xxxx sec" line to debug output for
                product queue scanners (pqcat, pqact, etc.), to
                display the delay between when a product is inserted
                into the product queue and when the queue scanner
                begins to process it.  This is useful in assessing
                pqact delay, for example.


You can use the "kill -USR2" command using the pqact program id
to cycle the logging between silent, verbose and debug logging
in order to place your running pqact into debug mode for looking
at the delay information, eg:

Jan 08 17:48:36 shemp.unidata.ucar.edu pqact[23652]: Adding debug
Jan 08 17:48:36 shemp.unidata.ucar.edu pqact[23652]: Delay: 1.3524 sec
Jan 08 17:48:36 shemp.unidata.ucar.edu pqact[23652]: 
   fd721bfe2c0d3e3f0fcddcaf50336148     5012 20020108174835.294     
   HDS 986  HVII25 EGRR 081200 /mU


If you find that a large lag in processing time occurs between 
when a product is placed in the queue, and when it is processed by pqact,
you can use multiple pqact and configuration file invocations from your 
ldmd.conf.

For example, I have 1 pqact process that only processes NEXRAD data:
<snip from ldmd.conf>
exec    "pqact"
exec    "pqact -f NNEXRAD /local/ldm/etc/pqact.nexrad"

The pqact.nexrad has pattern actions related to the NEXRAD data. The
standard pqact.conf is used by the first pqact process. In this way, the
queue processing is distributed. 

Steve Chiswell
Unidata User Support