[gradsusr] wrestling with LATS4d

[Arlindo da Silva]

On Wed, Apr 20, 2011 at 6:18 AM, Becker, Bernd <
bernd.becker at metoffice.gov.uk> wrote:

>
> Hello,
>
> Thanks for the development and provision of the lats interface!
> It is really handy and works very well (most of the time)
>
> I am sub selecting and regridding an ensemble forecast and hindcast.
> Lats does it's thing but occasionally , I get
>
> LATS warning (lats_parmtab: Closing the previously opened Parameter
> Table: /home/fred/blogs/misc.table
>
>
> and very occasionally, after about 15-20 minutes and grubbing through
> ca 20-40 files, I get
>
> LATS warning (lats_parmtab): Closing the previously opened Parameter
> Table:
> /home/fred/blogs/misc.table
> /home/fred/blogs/grads/gdopmod.ksh[193]: 496646 Segmentation
> fault(coredump)
>
>
> I wonder if this is caused by the following:
> in the grads script two files are opened:
> the input file and a dummy file to describe the new grid
>
> 'lats4d -v -table /home/fred/blogs/misc.table -de
> /home/fred/blogs/dummy.ctl -vars tmin tmax prec mslp z -func
> re(@,192,linear,0,1.875,145,linear,-90.00,1.25,ba) -lon 0 357.1875 -o
> 'outfile' -precision 12  -format grads_grib '
>
> Now I added a 'sleep 2' to give lats a breather and to sort out all
> internal I/O.
>
> and here I have choice: either
> - reinit or
> - close 2, close 1
>
> before the loop goes to the next file.
>
> But is does not change the error.
>
> All runs well, singing and dancing for about 20 minutes, then seg
> faults.
>
> Restarting the suite to continue working throught the list of files
> works fine for
> another batch of files until seg fault.
>
>
> What is there to try to pin point the problem?
>

Hmm... Very strange. This sort of problem usually indicates a memory leak
somewhere. Sometimes you simply get a segfault when you run out of memory.
If you are on a linux/unix environment, open a second window and start the
"top" command and watch the memory usage of your application (on Windows,
watch your memory usage from the task manager with ctrl-alt-del). If it
keeps going up until it segfaults this will confirm the memory leak. As for
fixing it, it will require some detective work by the developers.

I myself use the lats4d.sh script and issue the command from the shell
script, usually one file at a time.

    Arlindo

-- 
Arlindo da Silva
dasilva at alum.mit.edu
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