如何产生n个线程？

Question

我正在尝试编写一个多线程程序,基于命令行输入的线程数,所以我不能硬编码预先声明的线程.这是一种有效的方法吗？

int threads = 5; // (dynamic, not hard-coded)
int i = 0;
pthread_t * thread = malloc(sizeof(pthread_t)*threads);

for (i = 0; i < threads; i++) {
    pthread_t foobar;
    thread[i] = foobar; // will this cause a conflict?
}

for (i = 0; i < threads; i++) {

    int ret = pthread_create(&thread[i], NULL, (void *)&foobar_function, NULL);

    if(ret != 0) {
        printf ("Create pthread error!\n");
        exit (1);
    }
}

---

以下是我在下面建议的修改结果.似乎工作得很好.

int threads = 5;
int i;

pthread_t * thread = malloc(sizeof(pthread_t)*threads);

for (i = 0; i < threads; i++) {

    int ret = pthread_create(&thread[i], NULL, &foobar_function, NULL);

    if(ret != 0) {
        printf ("Create pthread error!\n");
        exit (1);
    }
    // pthread_join(thread[i], NULL); // don't actually want this here :)
}

sleep(1);     // main() will probably finish before your threads do,
free(thread); // so we'll sleep for illustrative purposes

Answer 1

第一个周期是什么？它是否将数组元素设置为未初始化的值？

所以我认为这就是你需要的:

int threads = 5, i = 0, ret = -1;

pthread_t * thread = malloc(sizeof(pthread_t)*threads);

for (i = 0; i < threads; i++) {

    ret = pthread_create(&thread[i], NULL, &foobar_function, NULL);

    if(ret != 0) {
        printf ("Create pthread error!\n");
        exit (1);
    }
}

它产生线程线程,在每个线程中启动foob​​ar_function.你有(如果一切顺利):)他们在线程数组中的ID .例如,您可以通过调用pthread_cancel(thread[1])等取消第二个线程.