I have a strange problem freeing allocated memory in my mpi program:
Here is a code sample that produces the error for me:
void *out, *in;
int cnt = 2501; //if cnt<=2500: works perfectly. cnt>2500: crashes at free!
if((out = malloc(cnt * sizeof(double))) == NULL)
MPI_Abort(MPI_COMM_WORLD, MPI_ERR_OP);
if((in = malloc(cnt * sizeof(double))) == NULL)
MPI_Abort(MPI_COMM_WORLD, MPI_ERR_OP);
//Test data generation
//usage of MPI_Send and MPI_Reduce_local
//doing a lot of memcpy, assigning pointer synonyms to in and out, changing data to in and out
free(in); //crashes here with "munmap_chunk(): invalid pointer"
free(out); //and here (if above line is commented out) with "double free or corruption (!prev)"
I ran it using valgrind:
mpirun -np 2 valgrind --leak-check=full --show-reachable=yes ./foo
and got the following:
==6248== Warning: ignored attempt to set SIGRT32 handler in sigaction();
==6248== the SIGRT32 signal is used internally by Valgrind
cr_libinit.c:183 cri_init: sigaction() failed: Invalid argument
==6248== HEAP SUMMARY:
==6248== in use at exit: 0 bytes in 0 blocks
==6248== total heap usage: 1 allocs, 1 frees, 25 bytes allocated
==6248==
==6248== All heap blocks were freed -- no leaks are possible
==6248==
=====================================================================================
= BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
= EXIT CODE: 134
Any ideas about how to track this error down? Note that it only appears if cnt>2500!
If you’re using GNU glibc, you can set the environment variable MALLOC_CHECK_ to 2 before running your program, to enable extra checking on memory-allocation calls—details here.