| Re: Performance issues [message #31171] |
Fri, 21 June 2002 13:10 |
Brian Jackel
Messages: 34
Registered: January 1998
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Member |
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Hi Sean
As David says, there isn't really a common cause for this.
I have IDL code that runs for days on large data sets, and
the processing time remains constant per number of elements.
There may be leaks in IDL, but I'm not seeing them.
You could post some code examples and see if the combined
"brain trust" notices anything funny.
Brian
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| Re: Performance issues [message #31173 is a reply to message #31171] |
Fri, 21 June 2002 08:42  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Sean Raffuse (sean@me.wustl.edu) writes:
> I have a batch routine that does a number of manipulations on large data
> sets (multi-dimensional arrays). The program works fine. However, it has
> slowdown problems. The program processes the datasets one at a time. The
> first one takes about 15 minutes or so. By the fourth or fifth dataset,
> the processing time is about double. This question may be too general, but
> what are the common causes for this in IDL? I can watch my memory usage in
> the task manager and it is not increasing. Since you can't use delvar
> outside of the main program, what else can I do?
You can try UNDEFINE, which works to undefine or delete
a variable at any program level:
http://www.dfanning.com/programs/undefine.pro
> Does this even matter?
I don't know. Certainly can't hurt to try.
I'm not sure there are "common causes" of slowdowns
in IDL. There can certainly be memory fragmentation
problems, but normally IDL is pretty good at managing
its own memory. I've never in my life written a program
that takes more than about 15 seconds to execute, so
I have no experience with something that takes 15 minutes.
I wonder if the slowdown can be machine dependent?
Just yesterday I managed to put IDL into an infinite
loop with a stupid programming error. After I had
exited IDL with Task Manager and fixed the problem,
my Windows machine was still dead slow. In the end,
the only way to fix the problem was to reboot. I don't
know if I had overextended Windows resources or what.
But I guess if you are working on something for 15
minutes or more that kind of thing might happen.
Cheers,
David
--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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