bombing out writing large scratch files

[Matthew Knepley]

The best thing to do here is get a stack trace from the debugger. From the
description, it is hard to tell what statement is trying to access which
illegal
memory.

   Matt

On 5/27/06, Randall Mackie <randy at geosystem.us> wrote:
>
> In my PETSc based modeling code, I write out intermediate results to a
> scratch
> file, and then read them back later. This has worked fine up until today,
> when for a large model, this seems to be causing my program to crash with
> errors like:
>
> ------------------------------------------------------------------------
> [9]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation,
> probably memory access out of range
>
>
> I've tracked down the offending code to:
>
>            IF (rank == 0) THEN
>              irec=(iper-1)*2+ipol
>              write(7,rec=irec) (xvec(i),i=1,np)
>            END IF
>
> It writes out xvec for the first record, but then on the second
> record my program is crashing.
>
> The record length (from an inquire statement) is  recl     22626552
>
> The size of the scratch file when my program crashes is 98M.
>
> PETSc is compiled using the intel compilers (v9.0 for fortran),
> and the users manual says that you can have record lengths of
> up to 2 billion bytes.
>
> I'm kind of stuck as to what might be the cause. Any ideas from anyone
> would be greatly appreciated.
>
> Randy Mackie
>
> ps. I've tried both the optimized and debugging versions of the PETSc
> libraries, with the same result.
>
>
> --
> Randall Mackie
> GSY-USA, Inc.
> PMB# 643
> 2261 Market St.,
> San Francisco, CA 94114-1600
> Tel (415) 469-8649
> Fax (415) 469-5044
>
> California Registered Geophysicist
> License No. GP 1034
>
>


-- 
"Failure has a thousand explanations. Success doesn't need one" -- Sir Alec
Guiness
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