MPI_Waitsome分段錯誤？

Question

我有類似：

int numprocs, id, arr[10], winner = -1; 
bool stop = false; 
MPI_Request reqs[10], winnerNotification; 

MPI_Init(NULL, NULL); 
MPI_Comm_size(MPI_COMM_WORLD, &numprocs); 
MPI_Comm_rank(MPI_COMM_WORLD, &id); 

srand(time(NULL) + id); 

if (id == 10) { 
    int completed = 0; 
    int* completedIndexes; 
    for (int i = 0; i < 10; i++) { 
     MPI_Irecv(&arr[i], 1, MPI_INT, i, 0, MPI_COMM_WORLD, &reqs[i]); 
    } 
    MPI_Waitsome(10, reqs, &completed, completedIndexes, MPI_STATUSES_IGNORE); 
    cout << completed << " seems to have completed" << endl; 
    for (int i = 0; i < completed; i++) { 
     cout << completedIndexes[i] << " have completed!"; 
    } 
} 

while (id < 10 && winner == -1) { 
    if (((rand() % 100) + 1) < 5) { // players have 5% chance of completing 
     MPI_Send(&id, 1, MPI_INT, 10, 0, MPI_COMM_WORLD); 
     cout << id << " completed" << endl; 
     MPI_Wait(&winnerNotification, MPI_STATUS_IGNORE); 
    } 
} 

MPI_Finalize(); 

這是給分段錯誤，我認爲它是與Waitsome？但是什麼？錯誤的樣子：

1 completed 
[JM:01317] *** Process received signal *** 
[JM:01317] Signal: Segmentation fault (11) 
[JM:01317] Signal code: Address not mapped (1) 
[JM:01317] Failing at address: 0x646574 
4 completed 
5 completed 
[JM:01320] *** Process received signal *** 
[JM:01320] Signal: Segmentation fault (11) 
[JM:01320] Signal code: Address not mapped (1) 
[JM:01320] Failing at address: 0x646574 
3 completed 
[JM:01319] *** Process received signal *** 
[JM:01319] Signal: Segmentation fault (11) 
[JM:01319] Signal code: Address not mapped (1) 
[JM:01319] Failing at address: 0x646574 
... 

Answer 1

MPI_Waitsome預計整數數組，它存儲的完成的請求的指標，但你給它的是一個未初始化的int指針。鑑於您已將10硬編碼爲請求數，請使用以下代碼：

if (id == 10) { 
    int completed = 0; 
    int completedIndexes[10]; 
    for (int i = 0; i < 10; i++) { 
     MPI_Irecv(&arr[i], 1, MPI_INT, i, 0, MPI_COMM_WORLD, &reqs[i]); 
    } 
    MPI_Waitsome(10, reqs, &completed, completedIndexes, MPI_STATUSES_IGNORE); 
    cout << completed << " seems to have completed" << endl; 
    for (int i = 0; i < completed; i++) { 
     cout << completedIndexes[i] << " have completed!"; 
    } 
}