[Wrf-users] Bug in WRF 3.2.1 RSL_LITE library

[Kemp, Eric M. (GSFC-610.0)[NORTHROP GRUMMAN INFORMATION TECH]]

Dear wrfhelp:

I continue to investigate a problem I reported several months ago:  occasional CFL errors and/or crashes with identical initial conditions when running a particular domain.  While I have not found a solution to this problem, I have found a bug in the RSL_LITE library.

In WRFV3/external/RSL_LITE/c_code.c, function RSL_LITE_INIT_EXCH contains two local variables (nbytes_x_recv and nbytes_y_recv).  These variables are declared without initial values.  If the code is compiled with MPI support, these variables are assigned values within if blocks (i.e., under special conditions; in some cases the statements in the if blocks are not executed).  If RSL_LITE is compiled serially, then the if statements are removed by the preprocessor.   At the end of the function (near line 300), these variables are used to calculate xp_curs_recv and yp_curs_recv.

My bug patch:

Near line 229:

#ifndef STUBMPI
  MPI_Comm comm, *comm0, dummy_comm ;

  nbytes_x_recv = 0; /* Bug fix */
  nbytes_y_recv = 0; /* Bug fix */

  comm0 = &dummy_comm ;

Near line 295:

       buffer_for_proc ( xm , nbytes, RSL_SENDBUF ) ;
    }
  }
#else  /* Bug fix */
  nbytes_x_recv = 0; /* Bug fix */
  nbytes_y_recv = 0; /* Bug fix */
#endif
  yp_curs = 0 ; ym_curs = 0 ; xp_curs = 0 ; xm_curs = 0 ;

I found this bug using ifort 11.1.038 and the “-check” compiler flag.

Cheers,

-Eric

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Eric M. Kemp                   Northrop Grumman Corporation
Meteorologist                  Information Systems
Civil Enterprise Solutions     Civil Systems Division

                               Goddard Space Flight Center
                               Mailstop 610.3
                               Greenbelt, MD 20771
                               Telephone   301-286-9768
                               Fax         301-286-1775
                               E-mail:     eric.kemp at nasa.gov
                               E-mail:     eric.kemp at ngc.com
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