20040323: gpmap in pqact?

Gerry,

As has already been pointed out, I did post a script for EXEC from pqact
that employs a load balancing file lock that allows one process at a
time. It will get the job done, and will protect against falling
behind of restart from an outage or queue remake.

I'd recommend against piping to a script for generation directly since
when you first start up an LDM with an empty queue, you will get a slug
of 1 hour's worth of NEXRAD products in short sequence. You would either
have several hundred instances of a generation script running, or
several hundred scripts waiting for PIPE input. The EXEC action
following the FILE action allows you to separate the generation action.
It also allows you to control your logic for scenarios when generation
may be falling behind.

Other alternatives are:

1) Use the 1km radar mosaic GINI and create regional sectors which are 
fewer than the number of NEXRAD sites (eg from SECTOR or GPMAP).

2) Use a cgi type of web script for on demand access (which may
eliminate the need to draw lots of boring images at the expense of
drawing some multiple times). An example using the radmap_sw gempak
program is available at:
http://motherlode.ucar.edu/unidata/images/nids/
The cgi for the above will create the gif file, and then cat it to the
browser using an image/gif type for the page.

Steve Chiswell

On Mon, 2004-03-22 at 20:57, Gerry Creager N5JXS wrote:
> Is there any way to pipe the incoming nexrad Level III data to gpmap in 
> pqact, if one is doing individual sites, so that a system isn't taken to 
> its knees every time a cron job fires that looks at every site?
> 
> Seems that if we could pipe it, we could spread out the load.  Or, am I 
> missing something fundamental?
> 
> Thanks!
> Gerry