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MathGroup Archive 2006

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Re: Re: "No more memory available" -- a recurring problem

  • To: mathgroup at smc.vnet.net
  • Subject: [mg68401] Re: Re: [mg68356] "No more memory available" -- a recurring problem
  • From: "Charlie Brummitt" <cbrummitt at wisc.edu>
  • Date: Wed, 2 Aug 2006 15:20:55 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

J=E1nos,

Thanks for the advice. I'm not really sure how to interpret the
information in the terminal window, so I have attached screenshots of
it at various stages (see the names of the images). I have attached
them in chronological order.

[Attachments are not allowed - please contact the author to get
them - moderator]

It seems to me that Mathematica is only being allocated 50% of the CPU
and 100 megabytes of RAM! When I did the "top" on my 12" PowerBook,
93% of the CPU was being used while Mathematica was running my code.
How do I change this on my 15" MacBook Pro?

My 12" PowerBook is able to run this code overnight and very rarely
gives the "ran out of memory" error message. I would like to be able
to run my code overnight on my MacBook Pro, but it can only run for 5
to 10 minutes before it runs out of memory and completely halts. Thus
I can't "set it and leave it"; instead, I must always be at my
computer to restart the calculation every 5 to 10 minutes. Any
suggestions?


Thanks for all your help, J=E1nos.

Charlie

On 8/2/06, J=E1nos <janos.lobb at yale.edu> wrote:
>
> On Aug 2, 2006, at 5:24 AM, Charlie Brummitt wrote:
>
> > I keep getting the following error message while running a search
> > of many PDE's:
> >
> > "No more memory available.
> > Mathematica kernel has shut down.
> > Try quitting other applications and then retry."
> >
> > This message is becoming so common that it is crippling my research
> > project, which is to find the simplest PDE with one quadratic
> > nonlinearity that is chaotic.
> >
> > I have Googled and searched the Mathgroup archives for help, and I
> > employed the following fixes:
> >
> > --CODE & SOFTWARE--
> > 1) Share[] -- does not help because my code rarely has common elements
> > that Share[] could consolidate.
> >
> > 2) I used Module[] and made as many variables local as possible. I
> > eliminated extra variables and functions in addition to adding Clear[]
> > in several places in the code to clear variables that are no longer
> > needed.
> >
> > 3) I streamlined and optimized the code in general, and I made the
> > routines as simple and least data-intensive as possible.
> >
> > 4) I never have any other applications open when running Mathematica.
> > (Unfortunately, closing other applications is the only suggestion that
> > Mathematica provides in the "out of memory" error message.)
> >
> > 5) I should note that I run the latest version of Mathematica
> > (5.2.2.0).
> >
> > --HARDWARE--
> > 1) I upgraded from a 12" PowerBook to a 15" MacBook Pro. This computer
> > has an 2.16 GHz Intel Core Duo processor.
> >
> > 2) I upgraded the RAM on this new computer from 1 GB to 2 GB.
> >
> > 3) I now have much more free hard drive space (20 GB) in case
> > Mathematica needs to use virtual memory. In addition, this hard drive
> > is 7200 rpm versus the standard 5400 rpm.
> >
> >
> > I have been using functions like MemoryInUse[] and On[MemoryConserve]
> > to monitor the use of memory. I almost always find that I am only
> > using a few megabytes at a time (usually 5-10 MB, sometimes as high as
> > 100 or once 1000 after a large computation). However, despite finding
> > that I usually use only a few megabytes during my computations, I
> > often get the above "out of memory" error message, and I can never
> > figure out why and how much memory was needed in that particular
> > computation.
> >
> >
> > Some questions:
> > 1) How can I tell whether Mathematica is using virtual memory or not?
> > It seems to me that it is not. I have 20 GB of hard drive space free
> > and it never seems to use it. Why should I ever run out of memory if I
> > have 20 GB free in case it needs more memory than my RAM provides?
> >
> > 2) Is there a way to determine how much of my 2 GB of RAM are
> > allocated to Mathematica? Can I increase how much RAM Mathematica can
> > access?
> >
> > Thanks in advance for any help you may be able to provide! I greatly
> > appreciate it. If you need more information on my code or the
> > computations I am doing, I would be happy to provide it.
> >
> > Regards,
> > Charlie
>
> If you open a Terminal window on the side and type "top" and hit
> return and start up your application, what do You see for real memory
> usage for the kernel and the front end from top?
>
> J=E1nos


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