我正在尝试使用 MPI 编写一个简单的程序,该程序可以找到所有小于 514 的数字,这些数字等于它们的数字之和的指数(例如,512 = (5+1+2)^3。问题我have 与主循环有关 - 它在几次迭代(c = 10)上工作得很好,但是当我尝试增加迭代次数(c = x)时,mpiexec.exe 只是挂起 - 似乎在 printf 例程的中间.
我很确定死锁是罪魁祸首,但我找不到任何问题。
源代码:
#include <stdlib.h>
#include <stdio.h>
#include <iostream>
#include "mpi.h"
int main(int argc, char* argv[])
{
//our number
int x=514;
//amount of iterations
int c = 10;
//tags for message identification
int tag = 42;
int tagnumber = 43;
int np, me, y1, y2;
MPI_Status status;
/* Initialize MPI */
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &np);
MPI_Comm_rank(MPI_COMM_WORLD, &me);
/* Check that we run on more than two processors */
if (np < 2)
{
printf("You have to use at least 2 processes to run this program\n");
MPI_Finalize();
exit(0);
}
//begin iterations
while(c>0)
{
//if main thread, then send messages to all created threads
if (me == 0)
{
printf("Amount of threads: %d\n", np);
int b = 1;
while(b<np)
{
int q = x-b;
//sends a number to a secondary thread
MPI_Send(&q, 1, MPI_INT, b, tagnumber, MPI_COMM_WORLD);
printf("Process %d sending to process %d, value: %d\n", me, b, q);
//get a number from secondary thread
MPI_Recv(&y2, 1, MPI_INT, b, tag, MPI_COMM_WORLD, &status);
printf ("Process %d received value %d\n", me, y2);
//compare it with the sent one
if (q==y2)
{
//if they're equal, then print the result
printf("\nValue found: %d\n", q);
}
b++;
}
x = x-b+1;
b = 1;
}
else
{
//if not a main thread, then process the message sent and send the result back.
MPI_Recv (&y1, 1, MPI_INT, 0, tagnumber, MPI_COMM_WORLD, &status);
int sum = 0;
int y2 = y1;
while (y1!=0)
{
//find the number's sum of digits
sum += y1%10;
y1 /= 10;
}
int sum2 = sum;
while(sum2<y2)
{
//calculate the exponentiation
sum2 = sum2*sum;
}
MPI_Send (&sum2, 1, MPI_INT, 0, tag, MPI_COMM_WORLD);
}
c--;
}
MPI_Finalize();
exit(0);
}
我将编译后的 exe 文件作为“mpiexec.exe -n 4 lab2.exe”运行。我使用 HPC Pack 2008 SDK,如果这对你们有用的话。
有什么办法可以解决吗?或者也许有某种方法可以正确调试这种情况?
提前非常感谢!