Question

了解pthreads，但我无法创建它们。这是我的输出和gdb信息：

In main(), creating thread 1 
ERROR: return code from pthread_create() is 22 for thread 1
In main(), creating thread 2
ERROR: return code from pthread_create() is 22 for thread 2
In main(), creating thread 3
ERROR: return code from pthread_create() is 22 for thread 3
In main(), creating thread 4
ERROR: return code from pthread_create() is 22 for thread 4
In main(), creating thread 5
ERROR: return code from pthread_create() is 22 for thread 5

Program received signal SIGSEGV, Segmentation fault. 0xb7fb4d8a in
pthread_join (threadid=76038327, thread_return=0x0)
    at pthread_join.c:46 46 pthread_join.c: No such file or directory.

这是我的代码：

#include <stdlib.h>
#include <stdio.h>
#include <strings.h>
#include <errno.h>
#include <pthread.h>
#include <unistd.h>

#define SBUFSIZE 1025

char errorstr[SBUFSIZE];
FILE* inputfp[5];

void* f(void* inpFile) {
    fprintf(stderr, "%s\n", (char*)inpFile);
    return NULL;
}

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

    int i;

    /* Thread Variables */
    pthread_attr_t attr;
    pthread_t *th[argc-2]; //one thread for each input file

    /* allocate memory for the threads */
    for (i = 0; i < (argc-2); i++) {
        th[i] = (pthread_t *) malloc(sizeof(pthread_t)); 
        inputfp[i] = fopen(argv[i], "r");
        if (!inputfp[i]) {
            sprintf(errorstr, "Error Opening Input File: %s", argv[i]);
            perror(errorstr);
        }
    }

    /* Create one thread for each input file */
    for (i = 1; i < (argc - 1); i++) {
        fprintf (stderr, "In main(), creating thread %1d\n", i);
        int rc = pthread_create (th[i], &attr, f, inputfp[i-1]);
        if (rc) {
            printf("ERROR: return code from pthread_create() is %d for thread %d\n",
                rc, i);
        }
    }

    /* wait for the threads to finish */
    for (i = 1; i < (argc - 1); i++) {
        pthread_join(*th[i], 0);
    }

    return EXIT_SUCCESS;
}

我错过了什么，但我不知道是什么。有人可以帮忙吗？谢谢！

编辑：以下是我根据Joachim Pileborg的建议更改代码的方法。我仍然从pthread_create（）返回错误22，但pthread_join上的SIGSEGV错误不再发生。

任何人都有关于如何让pthread_create（）返回0（表示创建成功的线程）的任何建议？再次感谢！

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

    int i;

    /* Thread Variables */
    pthread_attr_t attr;
    pthread_t *th[argc-2]; //one thread for each input file

    /* allocate memory for the threads */
    for (i = 0; i < (argc-2); i++) {
        th[i] = (pthread_t *) malloc(sizeof(pthread_t)); 
        printf("%s\n", argv[i+1]);
        inputfp[i] = fopen(argv[i+1], "r");
        if (!inputfp[i]) {
            sprintf(errorstr, "Error Opening Input File: %s", argv[i]);
            perror(errorstr);
        }
    }

    /* Create one thread for each input file */
    for (i = 0; i < (argc - 2); i++) {
        fprintf (stderr, "In main(), creating thread %1d\n", i);
        int rc = pthread_create (th[i], &attr, f, inputfp[i]);
        if (rc) {
            printf("ERROR: return code from pthread_create() is %d for thread %d\n",
                rc, i);
        }
    }

    /* wait for the threads to finish */
    for (i = 0; i < (argc - 2); i++) {
        pthread_join(*th[i], 0);
    }

    return EXIT_SUCCESS;
}

Answer 1

你有一个循环，你从零循环到argc - 3，并使用正确的索引（零到“数组的大小减一”。

然后你有两个循环从一个循环到argc - 2，并使用一个索引到“数组大小”。

你应该在所有三个地方使用与第一个相同的循环。

难以创建Pthreads（错误22）

1 个答案: