爲什麼我的線程不能正常產卵？ C

Question

這是我的代碼的縮寫版本。我應該澄清，「initializeGrid（）」的行爲是正確的，所以爲了簡潔起見，我沒有包括它。我試圖讓「threadFunction（）」在args中打印值，但它不起作用。請幫忙！

#include <pthread.h> 
#include <math.h> 
#include <stdio.h> 
#include <stdlib.h> 
#include <memory.h> 

int gridSize = 12; 

typedef struct threadParameter { 
    float * grid; 
    int top; 
    int bot; 
}threadParameter; 

void* threadFunction(void* args) { 

    threadParameter *param = (threadParameter*) args; 
    printf("%d, %d", param->bot, param->top); 
    return 0; 

} 

int main(int argc, char *argv[]) { 

    int numProcs = 4; 

    pthread_t * threadsArr = malloc(numProcs * sizeof(pthread_t)); 

    float mainGrid[gridSize][gridSize]; 
    memset(mainGrid, 0, gridSize*gridSize * sizeof(float)); 
    initializeGrid(1.0, 2.0, 3.0, 4.0, mainGrid); 

    threadParameter t = {&mainGrid[0][0], 0, gridSize}; 
    int ret = pthread_create(&threadsArr[0], 0, threadFunction, (void*)&t); 

} 

Answer 1

您的main()函數在調用pthread_create()後立即返回。

當main()返回時，進程退出並終止，同時生成每個線程。

您需要添加pthread_join()調用以等待線程終止。每pthread_join() POSIX standard：

的pthread_join()功能應暫停調用 線程的執行，直到目標thread終止

像這樣：

int main(int argc, char *argv[]) { 

    int numProcs = 4; 

    pthread_t * threadsArr = malloc(numProcs * sizeof(pthread_t)); 

    float mainGrid[gridSize][gridSize]; 
    memset(mainGrid, 0, gridSize*gridSize * sizeof(float)); 
    initializeGrid(1.0, 2.0, 3.0, 4.0, mainGrid); 

    threadParameter t = {&mainGrid[0][0], 0, gridSize}; 
    int ret = pthread_create(&threadsArr[0], 0, threadFunction, (void*)&t); 

    pthread_join(threadsArr[0], NULL); 
}