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In this C example, N clients loop MAX_WORK times. As part of a single work item, a client
must request service from one of Nservers at random. Each server
keeps a count of the requests handled and prints a log of the requests
to stdout. Once all the clients are done working, the servers are shutdown. |
#include <stdio.h>
#include <mpi.h>
#include <pthread.h>
#define MAX_WORK 40
#define SERVER_TAG 88
#define CLIENT_TAG 99
#define REQ_SHUTDOWN -1
static int service_cnt = 0;
int process_request(request)
int request;
{
if (request != REQ_SHUTDOWN) service_cnt++;
return request;
}
void* server(args)
void *args;
{
int rank, request;
MPI_Status status;
rank = *((int*)args);
while (1) {
MPI_Recv(&request, 1, MPI_INT, MPI_ANY_SOURCE,
SERVER_TAG, MPI_COMM_WORLD, &status);
if (process_request(request) == REQ_SHUTDOWN)
break;
MPI_Send(&rank, 1, MPI_INT, status.MPI_SOURCE,
CLIENT_TAG, MPI_COMM_WORLD);
printf("server [%d]: processed request %d for client %d\n",
rank, request, status.MPI_SOURCE);
}
printf("server [%d]: total service requests: %d\n", rank, service_cnt);
return (void*) 0;
}
void client(rank, size)
int rank;
int size;
{
int w, server, ack;
MPI_Status status;
for (w = 0; w < MAX_WORK; w++) {
server = rand()%size;
MPI_Sendrecv(&rank, 1, MPI_INT, server, SERVER_TAG, &ack,
1,MPI_INT,server,CLIENT_TAG,MPI_COMM_WORLD, &status);
if (ack != server) {
printf("server failed to process my request\n");
MPI_Abort(MPI_COMM_WORLD, MPI_ERR_OTHER);
}
}
}
void shutdown_servers(rank)
int rank;
{
int request_shutdown = REQ_SHUTDOWN;
MPI_Barrier(MPI_COMM_WORLD);
MPI_Send(&request_shutdown, 1, MPI_INT, rank, SERVER_TAG, MPI_COMM_WORLD);
}
main(argc, argv)
int argc;
char *argv[];
{
int rank, size, rtn;
pthread_t mtid;
MPI_Status status;
int my_value, his_value;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &size);
rtn = pthread_create(&mtid, 0, server, (void*)&rank);
if (rtn != 0) {
printf("pthread_create failed\n");
MPI_Abort(MPI_COMM_WORLD, MPI_ERR_OTHER);
}
client(rank, size);
shutdown_servers(rank);
rtn = pthread_join(mtid, 0);
if (rtn != 0) {
printf("pthread_join failed\n");
MPI_Abort(MPI_COMM_WORLD, MPI_ERR_OTHER);
}
MPI_Finalize();
exit(0);
} |
|
thread_safe
output | |
The output from running the thread_safe executable is shown
below. The application was run with -np = 2. |
server [1]: processed request 1 for client 1
server [0]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [1]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [1]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [0]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [0]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [0]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [1]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [1]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [0]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [1]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [0]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [1]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [1]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [0]: processed request 1 for client 1
server [0]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [1]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [1]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [0]: processed request 1 for client 1
server [1]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [0]: processed request 0 for client 0
server [0]: processed request 1 for client 1
server [0]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [1]: processed request 0 for client 0
server [1]: processed request 0 for client 0
server [1]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [1]: processed request 0 for client 0
server [0]: processed request 0 for client 0
server [1]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [0]: processed request 1 for client 1
server [1]: processed request 1 for client 1
server [0]: processed request 1 for client 1
server [0]: total service requests: 38
server [1]: total service requests: 42 |
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