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Subject: [OMPI users] MPI_Type_struct for structs with dynamic arrays
From: Jitendra Kumar (jkumar_at_[hidden])
Date: 2008-08-10 19:07:00


Hi,
I am trying to use MPI derived datatype doutines for sending a struct
which contains dynamically allocated arrays. I tried implementing it
using MPI_Type_struct. It doesn't throws any error but messages being
received (of the declared datatype) aren't correct. Some memory
corruption seems to be going on as the value of 'rank' at receive end
are changed to 0 right after the receive . Below are the snippets of my
struct and implementation of the derived datatype.
I am not sure where things are going wrong. I would highly appreciate
any pointers or suggestions. Is there any better alternative way instead
of MPI_Type_struct considering that frequent communication of these
structs are needed?

Thanks,
Jitendra

The struct looks like this:
     51 typedef struct
     52 {
     53 int *intvar;
     54 double *realvar;
     55 double *binvar;
     56 int **gene;
     57
     58 double *obj;
     59 double *constr;
     60 double constr_violation;
     61 double crowd_dist;
     62 int rank;
     63 double *strategyParameter;
     64 }
     65 individual;

Implementation of the derived datatype:

    483 blockcounts[0] = parentPop[0].numInteger;
    484 blockcounts[1] = parentPop[0].numReal;
    485 blockcounts[2] = parentPop[0].numBinary;
    486 sum = 0;
    487 for(i=0; i<parentPop[0].numBinary; i++)
    488 {
    489 sum = sum + parentPop[0].nbits[i];
    490 }
    491
    492 blockcounts[3] = sum;
    493 blockcounts[4] = parentPop[0].nobj;
    494 blockcounts[5] = parentPop[0].ncon;
    495 blockcounts[6] = 1;
    496 blockcounts[7] = 1;
    497 blockcounts[8] = 1;
    498 blockcounts[9] = parentPop[0].numInteger +
parentPop[0].numReal;

    506 types[0] = MPI_INT;
    507 types[1] = MPI_DOUBLE;
    508 types[2] = MPI_DOUBLE;
    509 types[3] = MPI_INT;
    510 types[4] = MPI_DOUBLE;
    511 types[5] = MPI_DOUBLE;
    512 types[6] = MPI_DOUBLE;
    513 types[7] = MPI_DOUBLE;
    514 types[8] = MPI_INT;
    515 types[9] = MPI_DOUBLE;
    516
    517 MPI_Get_address(&parentPop[0].indiv[0].intvar, &disp[0]);
    518 printf("parentpop.indiv0 %ld disp %ld (%ld)\n",
&parentPop[0].indiv[0], disp, disp[0]);
    519 MPI_Get_address(&parentPop[0].indiv[0].realvar, &disp[1]);
    520 printf("disp 1 %ld\n", disp[1]);
    521 MPI_Get_address(&parentPop[0].indiv[0].binvar, &disp[2]);
    522 printf("disp 2 %ld\n", disp[2]);
    523 MPI_Get_address(&parentPop[0].indiv[0].gene, &disp[3]);
    524 MPI_Get_address(&parentPop[0].indiv[0].obj, &disp[4]);
    525 MPI_Get_address(&parentPop[0].indiv[0].constr, &disp[5]);
    526 MPI_Get_address(&parentPop[0].indiv[0].constr_violation,
&disp[6]);
    527 MPI_Get_address(&parentPop[0].indiv[0].crowd_dist,
&disp[7]);
    528 MPI_Get_address(&parentPop[0].indiv[0].rank, &disp[8]);
    529
MPI_Get_address(&parentPop[0].indiv[0].strategyParameter, &disp[9]);
    530 base = disp[0];
    531 for(i=0; i<10; i++)
    532 {
    533 disp[i] -= base;
    534 }
    535
    536 MPI_Type_create_struct(10, blockcounts, disp, types,
&Individual);
    537
    538 /* Check that the datatype has correct extent */
    539 MPI_Type_extent(Individual, &extent);
    540 if(extent != sizeof(individual))
    541 {
    542 MPI_Datatype indold = Individual;
    543 MPI_Type_create_resized(indold, 0,
sizeof(individual), &Individual);
    544 MPI_Type_free(&indold);
    545 }
    546 MPI_Type_commit(&Individual);