Pierre,<div><br></div><div> We need to know the system you are running on. Version 1.8SL11 is old (ca. 2002?) and unless you redid your own build, chances are it is getting "out of sync" with the underlying system libraries. Upgrade if you can. GrADS v2 is getting more and more stable with each new release. The builds found at <a href="http://opengrads.org">http://opengrads.org</a> includes some useful extensions (e.g., regridding, shapefile support, poisson solver, spectral filters, etc) not yet found at the official COLA releases.<br>
<br></div><div> About parallelization, again you did not give us much detail. How exactly did you start your 2 copies of GrADS? I m assuming you are on the same *node*, attempting to start GrADS on different *cores*. In this case you may be sharing the system memory with each instance of GrADS you run. Any chance that you could be running out of memory? There are known memory leaks in v1.8SL11, specially with templated netcdf/hdf-4 files.</div>
<div><br></div><div> About starting several instances of grads concurrently. There are several options to do that. Depending on your OS, starting 2 versions of grads in the background from the shell (I am assuming a Unix like OS here)</div>
<div><br></div><div>% grads -lc 'run <a href="http://script1.gs">script1.gs</a>' &</div><div>% grads -lc 'run <a href="http://script2.gs">script2.gs</a>' &</div><div><br></div><div>will start each copy on separate cores. SGI's AIX on Altix processors would even dish out processes across nodes this way; most commonly the parallelization is done only within a single node. For going beyond a single node I've written a simple perl client/server script to go across nodes using mpirun (grads itself does not make use of MPI). I am attaching the perl script for reference; type prund.pl without arguments for a manual page.</div>
<div><br></div><div>If you are a python programmer, you could also also use the python thread class together with pygrads for starting concurrent grads instances. </div><div><br></div><div> Good Luck,</div><div><br></div>
<div> Arlindo</div><div><br></div><div><br><div class="gmail_quote">On Fri, Jul 10, 2009 at 2:36 PM, <span dir="ltr"><<a href="mailto:pierre.lacombe@mddep.gouv.qc.ca">pierre.lacombe@mddep.gouv.qc.ca</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div><p><img></p>
<div><font face="Arial" size="2"><span style="font-size:8.5pt;font-family:Tahoma"> </span></font></div>
<div>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span style="font-size:13.5pt;font-family:Tahoma">I work
for the Centre d'Expertise Hydrique du Québec (CEHQ,
<a href="http://www.cehq.gouv.qc.ca" target="_blank">http://www.cehq.gouv.qc.ca</a>), which is an agency of the Québec's ministry of
environment (formely the Ministère du développement durable et des parcs du
gouvernement du Québec). Among various objectives, the CEHQ operates the
hydrometric network of the </span><span style="font-size:13.5pt;font-family:Tahoma">province</span><span style="font-size:13.5pt;font-family:Tahoma"> of
</span><span style="font-size:13.5pt;font-family:Tahoma">Québec</span><span style="font-size:13.5pt;font-family:Tahoma"> and
supports the management of public dams by producing hydrological
forecasts.</span></p>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span style="font-size:13.5pt;font-family:Tahoma"> </span></p>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span style="font-size:13.5pt;font-family:Tahoma">Over
nearly ten years, our hydrological forecasts have been produced dayly at a 3h
timestep by integrating meteorological forecasts data of the canadian model GEM.
<span> </span>To process the GEM input data, we
use the GRADS system</span><span style="font-size:10pt;color:blue;font-family:Arial"> </span><span style="font-size:13.5pt;font-family:Tahoma">(Grid
Analysis and Display System (GrADS), version 1.8SL11. We run GRADS on a serial
computer, an it works perfectly well. However, recently we aquired a few
quadcores computers and found a way to make GRADS work in parallel for us. The
idea is simple, and consists to let GRADS 1 computes the temperature mean, while
GRADS 2 computes the precipitation in the same time. As a result, we save half
of the computing time every morning. This work almost fine, except that in
certains executions we have an error of initialisation of GRADS or GRADS
sometimes freezes. So we are unable to use this idea for
now.</span></p>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span style="font-size:8.5pt;font-family:Tahoma"> </span></p>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span style="font-size:13.5pt;font-family:Tahoma">We
wonder if there is a version of GRADS that works in parallel, or are there some
limits to the use of GRADS that we should know, and that we could overpass with
some adjustments.</span></p>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span style="font-size:8.5pt;font-family:Tahoma"> </span></p>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span style="font-size:13.5pt;font-family:Tahoma">We
thank you in advance for any technical assistance you may kindly provide to us,
or for your help by transmitting this message to a colleague that may better
answer to these questions.</span></p>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span><font face="Times New Roman" size="3"> </font></span></p>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span style="font-size:13.5pt;font-family:Tahoma">Best
Regards,</span></p>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span style="font-size:13.5pt;font-family:Tahoma"> </span></p>
<p style="margin:0cm 0cm 0pt;text-align:justify"><span style="font-size:13.5pt;font-family:Tahoma">Pierre
Lacombe, computer analyst</span></p></div></div>
</blockquote></div><br><br clear="all"><br>-- <br>Arlindo da Silva<br><a href="mailto:dasilva@alum.mit.edu">dasilva@alum.mit.edu</a><br>
</div>