MPI: Sending an array of a structure containing a pointer

Question

I have got the following C structure:

typedef struct chromosome{
int *genes;
float cout;
}chromosome;

I would like to send an array of chromosomes using MPI_Send. I've defined an MPI_CHROMOSOME data type like this:

MPI_Datatype MPI_CHROMOSOME;
MPI_Datatype TYPES_ELEMENTAIRES[2] = {MPI_INT, MPI_FLOAT};
int blocklengths[2] = {NB_SOMMETS,1}; //NB_SOMMET is a known integer value at this point (number of elements of the "genes" array)
MPI_Aint offsets[2];

offsets[0] = offsetof(chromosome, genes);
offsets[1] = offsetof(chromosome, cout);

MPI_Type_create_struct(2, blocklengths, offsets, TYPES_ELEMENTAIRES, &MPI_CHROMOSOME);
MPI_Type_commit(&MPI_CHROMOSOME);

Then I tried to send an array of chromosomes:

chromosome *sub_pop = malloc(taille_sub_pop*sizeof(chromosome));//taille_sub_pop is a known integer value
/* ... Fills sub_pop with chromosomes ...*/
MPI_Send(sub_pop,taille_sub_pop,MPI_CHROMOSOME, 1, 3, MPI_COMM_WORLD);

... But I got an error (BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES... Exit Code 139... YOUR APPLICATION TERMINATED WITH THE EXIT STRING: Segmentation fault (signal 11)).

How can I send this array properly ? I would appreciate your help. Thanks a lot.

Community · Accepted Answer · 2017-05-23 10:28:36Z

2

You can't send pointers to other processes with MPI. Well, technically you can, but because each process has its own memory space and addressing, a pointer that was valid on one process will most likely point to invalid memory on another. Anyway, you want to send the data that the pointer is pointing to, not the pointer itself.

See this question: Creating an MPI_Datatype for a structure containing pointers

edited May 23, 2017 at 10:28

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answered May 21, 2016 at 15:52

suszterpatt

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1 Comment

Reda94 Over a year ago

Hi, thanks for your answer. In the link that you sent me, I actually want to send an array of that kind of structure, not only one element...

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