bombing out writing large scratch files

[Randall Mackie]

This is a stupid question, but how do I start in the debugger if I'm running
on a cluster half-way around the world and I'm working on that cluster
via ssh?

Randy


Matthew Knepley wrote:
> 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 
> <mailto: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

-- 
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