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Subject: Re: [OMPI users] machine exited on signal 11 (Segmentation fault).
From: Jeffrey Squyres (jsquyres_at_[hidden])
Date: 2012-04-18 08:11:56


As a guess, you're passing in a bad address.

Double check the buffers that you're sending to MPI_SEND/MPI_RECV/etc.

On Apr 17, 2012, at 10:43 PM, Rohan Deshpande wrote:

> After using malloc i am getting following error
>
> *** Process received signal ***
> Signal: Segmentation fault (11)
> Signal code: Address not mapped (1)
> Failing at address: 0x1312d08
> [ 0] [0x5e840c]
> [ 1] /usr/local/lib/openmpi/mca_btl_tcp.so(+0x5bdb) [0x119bdb]
> /usr/local/lib/libopen-pal.so.0(+0x19ce0) [0xb2cce0]
> /usr/local/lib/libopen-pal.so.0(opal_event_loop+0x27) [0xb2cf47]
> /usr/local/lib/libopen-pal.so.0(opal_progress+0xda) [0xb200ba]
> /usr/local/lib/openmpi/mca_pml_ob1.so(+0x3f75) [0xa9ef75]
> [ 6] /usr/local/lib/libmpi.so.0(MPI_Recv+0x136) [0xea7c46]
> [ 7] mpi_array(main+0x501) [0x8048e25]
> [ 8] /lib/libc.so.6(__libc_start_main+0xe6) [0x2fece6]
> [ 9] mpi_array() [0x8048891]
> *** End of error message ***
> [machine4][[3968,1],0][btl_tcp_frag.c:216:mca_btl_tcp_frag_recv] mca_btl_tcp_frag_recv: readv failed: Connection reset by peer (104)
> --------------------------------------------------------------------------
> mpirun noticed that process rank 1 with PID 2936 on node machine4 exited on signal 11 (Segmentation fault).
>
> Can someone help please.
>
> Thanks
>
>
>
> On Tue, Apr 17, 2012 at 6:01 PM, Jeffrey Squyres <jsquyres_at_[hidden]> wrote:
> Try malloc'ing your array instead of creating it statically on the stack. Something like:
>
> int *data;
>
> int main(..) {
> {
> data = malloc(ARRAYSIZE * sizeof(int));
> if (NULL == data) {
> perror("malloc");
> exit(1);
> }
> // ...
> }
>
>
> On Apr 17, 2012, at 5:05 AM, Rohan Deshpande wrote:
>
> >
> > Hi,
> >
> > I am trying to distribute large amount of data using MPI.
> >
> > When I exceed the certain data size the segmentation fault occurs.
> >
> > Here is my code,
> >
> >
> > #include "mpi.h"
> > #include <stdio.h>
> > #include <stdlib.h>
> > #include <string.h>
> > #define ARRAYSIZE 2000000
> > #define MASTER 0
> >
> > int data[ARRAYSIZE];
> >
> >
> > int main(int argc, char* argv[])
> > {
> > int numtasks, taskid, rc, dest, offset, i, j, tag1, tag2, source, chunksize, namelen;
> > int mysum, sum;
> > int update(int myoffset, int chunk, int myid);
> > char myname[MPI_MAX_PROCESSOR_NAME];
> > MPI_Status status;
> > double start, stop, time;
> > double totaltime;
> > FILE *fp;
> > char line[128];
> > char element;
> > int n;
> > int k=0;
> >
> >
> >
> > /***** Initializations *****/
> > MPI_Init(&argc, &argv);
> > MPI_Comm_size(MPI_COMM_WORLD, &numtasks);
> > MPI_Comm_rank(MPI_COMM_WORLD,&taskid);
> > MPI_Get_processor_name(myname, &namelen);
> > printf ("MPI task %d has started on host %s...\n", taskid, myname);
> > chunksize = (ARRAYSIZE / numtasks);
> > tag2 = 1;
> > tag1 = 2;
> >
> >
> > /***** Master task only ******/
> > if (taskid == MASTER){
> >
> > /* Initialize the array */
> > sum = 0;
> > for(i=0; i<ARRAYSIZE; i++) {
> > data[i] = i * 1 ;
> > sum = sum + data[i];
> > }
> > printf("Initialized array sum = %d\n",sum);
> >
> > /* Send each task its portion of the array - master keeps 1st part */
> > offset = chunksize;
> > for (dest=1; dest<numtasks; dest++) {
> > MPI_Send(&offset, 1, MPI_INT, dest, tag1, MPI_COMM_WORLD);
> > MPI_Send(&data[offset], chunksize, MPI_INT, dest, tag2, MPI_COMM_WORLD);
> > printf("Sent %d elements to task %d offset= %d\n",chunksize,dest,offset);
> > offset = offset + chunksize;
> > }
> >
> > /* Master does its part of the work */
> > offset = 0;
> > mysum = update(offset, chunksize, taskid);
> >
> > /* Wait to receive results from each task */
> > for (i=1; i<numtasks; i++) {
> > source = i;
> > MPI_Recv(&offset, 1, MPI_INT, source, tag1, MPI_COMM_WORLD, &status);
> > MPI_Recv(&data[offset], chunksize, MPI_INT, source, tag2,
> > MPI_COMM_WORLD, &status);
> > }
> >
> > /* Get final sum and print sample results */
> > MPI_Reduce(&mysum, &sum, 1, MPI_INT, MPI_SUM, MASTER, MPI_COMM_WORLD);
> > /* printf("Sample results: \n");
> > offset = 0;
> > for (i=0; i<numtasks; i++) {
> > for (j=0; j<5; j++)
> > printf(" %d",data[offset+j]);ARRAYSIZE
> > printf("\n");
> > offset = offset + chunksize;
> > }*/
> > printf("\n*** Final sum= %d ***\n",sum);
> >
> > } /* end of master section */
> >
> >
> > #include <stdlib.h>
> > /***** Non-master tasks only *****/
> >
> > if (taskid > MASTER) {
> >
> > /* Receive my portion of array from the master task */
> > start= MPI_Wtime();
> > source = MASTER;
> > MPI_Recv(&offset, 1, MPI_INT, source, tag1, MPI_COMM_WORLD, &status);
> > MPI_Recv(&data[offset], chunksize, MPI_INT, source, tag2,MPI_COMM_WORLD, &status);
> >
> > mysum = update(offset, chunksize, taskid);
> > stop = MPI_Wtime();
> > time = stop -start;
> > printf("time taken by process %d to recieve elements and caluclate own sum is = %lf seconds \n", taskid, time);
> > totaltime = totaltime + time;
> >
> > /* Send my results back to the master task */
> > dest = MASTER;
> > MPI_Send(&offset, 1, MPI_INT, dest, tag1, MPI_COMM_WORLD);
> > MPI_Send(&data[offset], chunksize, MPI_INT, MASTER, tag2, MPI_COMM_WORLD);
> >
> > MPI_Reduce(&mysum, &sum, 1, MPI_INT, MPI_SUM, MASTER, MPI_COMM_WORLD);
> >
> > } /* end of non-master */
> >
> > // printf("Total time taken for distribution is - %lf seconds", totaltime);
> > MPI_Finalize();
> >
> > } /* end of main */
> >
> >
> > int update(int myoffset, int chunk, int myid) {
> > int i,j;
> > int mysum;
> > int mydata[myoffset+chunk];
> > /* Perform addition to each of my array elements and keep my sum */
> > mysum = 0;
> > /* printf("task %d has elements:",myid);
> > for(j = myoffset; j<myoffset+chunk; j++){
> > printf("\t%d", data[j]);
> > }
> > printf("\n");*/
> > for(i=myoffset; i < myoffset + chunk; i++) {
> >
> > //data[i] = data[i] + i;
> > mysum = mysum + data[i];
> > }
> > printf("Task %d has sum = %d\n",myid,mysum);
> > return(mysum);
> > }
> >
> >
> > When I run it with ARRAYSIZE = 2000000 The program works fine. But when I increase the size ARRAYSIZE = 20000000. The program ends with segmentation fault.
> > I am running it on a cluster (machine 4 is master, machine 5,6 are slaves) and np=20
> >
> > MPI task 0 has started on host machine4
> > MPI task 2 has started on host machine4
> > MPI task 3 has started on host machine4
> > MPI task 14 has started on host machine4
> > MPI task 8 has started on host machine6
> > MPI task 10 has started on host machine6
> > MPI task 13 has started on host machine4
> > MPI task 4 has started on host machine5
> > MPI task 6 has started on host machine5
> > MPI task 7 has started on host machine5
> > MPI task 16 has started on host machine5
> > MPI task 11 has started on host machine6
> > MPI task 12 has started on host machine4
> > MPI task 5 has started on hostmachine5
> > MPI task 17 has started on host machine5
> > MPI task 18 has started on host machine5
> > MPI task 15 has started on host machine4
> > MPI task 19 has started on host machine5
> > MPI task 1 has started on host machine4
> > MPI task 9 has started on host machine6
> > Initialized array sum = 542894464
> > Sent 1000000 elements to task 1 offset= 1000000
> > Task 1 has sum = 1055913696
> > time taken by process 1 to recieve elements and caluclate own sum is = 0.249345 seconds
> > Sent 1000000 elements to task 2 offset= 2000000
> > Sent 1000000 elements to task 3 offset= 3000000
> > Task 2 has sum = 328533728
> > time taken by process 2 to recieve elements and caluclate own sum is = 0.274285 seconds
> > Sent 1000000 elements to task 4 offset= 4000000
> > --------------------------------------------------------------------------
> > mpirun noticed that process rank 3 with PID 5695 on node machine4 exited on signal 11 (Segmentation fault).
> >
> > Any idea what could be wrong here?
> >
> >
> > --
> >
> > Best Regards,
> >
> > ROHAN DESHPANDE
> >
> >
> >
> > _______________________________________________
> > users mailing list
> > users_at_[hidden]
> > http://www.open-mpi.org/mailman/listinfo.cgi/users
>
>
> --
> Jeff Squyres
> jsquyres_at_[hidden]
> For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
>
>
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-- 
Jeff Squyres
jsquyres_at_[hidden]
For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/