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Re: IDL Memory Leaks [message #27677 is a reply to message #27673]

Mon, 05 November 2001 10:24

John-David T. Smith is currently offline

John-David T. Smith
Messages: 384
Registered: January 2000

Senior Member

Myron Brown wrote:
>
> Recently, I have noticed that my IDL programs leak memory, but I never
> use pointers directly. This is true when running with IDL on a Windows
> PC or on an SGI workstation. Widgets seem to be one source of
> problems. File I/O seems to be another, but I'm not yet sure. Due to
> the problems I'm having with memory leaks, my long runs eventually die
> when memory is exhausted.
>
> Does anyone have any hints on ways to avoid memory leaks in IDL?
>
> Please reply to my e-mail address, since I don't often use newsgroups.
>
> Thanks.

Myron:

Side point: comp.lang.idl is an altogether different newsgroup,
unrelated to RSI's IDL. Interface Definition Language, or some such.
Just FYI, because I'm sure they're as confused by our posts as we are by
theirs.

I can suggest a few places to look:

1. Pointers. Are you *sure* the widgets you use aren't compound
widgets with pointers in them, or that all your I/O routines are
pointer-free? You can, at any point, find out what's on the
object/pointer heap by:

IDL> help,/heap

If anything is on the heap, look for dangling pointer variables with:

IDL> heap_gc,/verbose

which will tell you *which* pointers were causing memory leaks.
Repeating this a few times can help you zero in on the culprit.

2. Widget's with large UVALUEs inside. Widgets are in many ways just
like pointers: they live on a global heap, are referenced by a unique
ID, and can point to not one, but several different values of different
sizes. This is perhaps why David Fanning used empty base widget's
UVALUEs as pointers in the good old days before "real" pointers were
introduced by RSI (possibly prompted by the embarrassment he was causing
them ;). If you're sticking very large things (like arrays) inside
widget UVALUE's, and not properly destroying these widgets, you'll be in
exactly the same boat as with pointer leaks.

Unfortunately, unlike pointers, there's not a nice way of investigating
what's on the "widget heap" at a given time, that I know of. You can
use the help,/MEMORY command to try to isolate big jumps, and even to
analyze the size being added. If it's close to an array size you're
sticking in a widget, then that's a very strong clue.

Good luck,

JD

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[Message index]

		Re: IDL Memory Leaks By: Myron Brown on Mon, 05 November 2001 13:58
		Re: IDL Memory Leaks By: David Fanning on Mon, 05 November 2001 13:21
		Re: IDL Memory Leaks By: Myron Brown on Mon, 05 November 2001 12:57
		Re: IDL Memory Leaks By: John-David T. Smith on Mon, 05 November 2001 10:24
		Re: IDL Memory Leaks By: David Fanning on Mon, 05 November 2001 10:22
		Re: IDL Memory Leaks By: John-David T. Smith on Tue, 06 November 2001 09:59
		Re: IDL Memory Leaks By: pit on Tue, 06 November 2001 07:15
		Re: IDL Memory Leaks By: Mark Hadfield on Mon, 05 November 2001 17:02
		Re: IDL Memory Leaks By: John-David T. Smith on Mon, 05 November 2001 14:22
		Re: IDL Memory Leaks By: Stein Vidar Hagfors H[1] on Tue, 06 November 2001 06:23
		Re: IDL Memory Leaks By: Jaco van Gorkom on Tue, 06 November 2001 05:16

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