四线程分割进程 C 程序中的“Segmentation fault: 11”错误

Question

我已经用 C 编写了我的第一个多线程程序。特别是：程序接收一个 int 参数，该参数指定 main 中 int 类型数组的大小。该数组将随机分配和填充。我想研究多线程程序和单线程程序之间的时间差异。因此，我编写了上述程序的两个“相同”版本。 “标准”程序运行良好，一切正常，例如：

$ ./prog 10000

all done

real    0m0.244s
user    0m0.238s
sys     0m0.004s

这是非线程程序的输出。

但是，当我运行线程程序时，我得到了这个错误：

Segmentation fault: 11

我已经看到这个错误代码是关于指针的错误（通常在分配的内存区域之外），但是这次我找不到我提交的错误/错误。会是累，会是我是初学者，但现在我看不到我的错误。有人可以帮我吗？

线程程序的源代码如下：

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

void *order(int * v, int x, int y);
void printv(int * v, int dim);

int main (int argc, const char *argv[]) {
    int *v = NULL;
    int x = 0;
    int dim = 0;
    pthread_t bot1 = NULL, bot2 = NULL, bot3 = NULL, bot4 = NULL;
    void *retval;

    if (argc != 2) {
        fprintf(stderr, "usage: %s [arraySize]\n", argv[0]);
        exit(EXIT_FAILURE);
    }
    dim = atoi(argv[1]);

    if (dim <= 0) {
        fprintf(stderr, "usage: %s [arraySize] in which [arraySize] must be an integer > 0\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    v = (int *) malloc (dim * sizeof (int));

    if (v == NULL) {
        fprintf(stderr, "array allocation error\n");
        exit(EXIT_FAILURE);
    }

    // Initial array
    fprintf(stdout, "the initial array is: ");
    printv(v, dim);
    fprintf(stdout, "\n\n");

    // Randomize array
    for (x = 0; x < dim; x++) {
        v[x] = rand()%100;
    }

    fprintf(stdout, "the randomized array is: ");
    printv(v, dim);
    fprintf(stdout, "\n\n");

    // Ordering array

    // WARNING: "OVERLAP SECTOR BEGIN"

    pthread_create(&bot1, NULL, order(v, 0, dim/4), NULL);
    pthread_create(&bot2, NULL, order(v, dim/4, dim/2), NULL);
    pthread_create(&bot3, NULL, order(v, dim/2, (dim/4)*3), NULL);
    pthread_create(&bot4, NULL, order(v, (dim/4)*3, dim), NULL);

    pthread_join(bot1, &retval);
    pthread_join(bot2, &retval);
    pthread_join(bot3, &retval);
    pthread_join(bot4, &retval);

    // WARNING: "OVERLAP SECTOR END"

    fprintf(stdout, "the ordered array is: ");
    printv(v, dim);
    fprintf(stdout, "\n\n");

    // End main
    fprintf(stdout, "all done\n");
    return 0;
}

void *order (int * v, int x, int y){
    int i = 0;
    int j = 0;
    int tmp = 0;

    for (i = x; i < y; i++) {
        for (j = x; j < y; j++) {
            if (v[i] < v[j]) {
                tmp=v[i];
                v[i]=v[j];
                v[j]=tmp;
            }
        }
    }

    return 0;
}

void printv (int * v,  int dim) {
    int x = 0;
    for (x = 0; x < dim; x++) {
        fprintf(stdout, "%d ", v[x]);
    }
    fprintf(stdout, "\n\n\n");
    return;
}

问候。

附： 错误发生在“重叠扇区”（在 cmets 中描述）之前和数组填充操作之后。

Answer 1

您错误地使用了 pthread_create。试试这个：

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

struct args {
    int* _v;
    int _x;
    int _y;
};

void *order(void *args_ptr);
void printv(int * v, int dim);

int main (int argc, const char *argv[]) {
    int *v = NULL;
    int x = 0;
    int dim = 0;
    pthread_t bot1 , bot2 , bot3 , bot4 ;
    void *retval;

    struct args args1;
    struct args args2;
    struct args args3;
    struct args args4;

    if (argc != 2) {
        fprintf(stderr, "usage: %s [arraySize]\n", argv[0]);
        exit(EXIT_FAILURE);
    }
    dim = atoi(argv[1]);

    if (dim <= 0) {
        fprintf(stderr, "usage: %s [arraySize] in which [arraySize] must be an integer > 0\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    v = (int *) malloc (dim * sizeof (int));

    if (v == NULL) {
        fprintf(stderr, "array allocation error\n");
        exit(EXIT_FAILURE);
    }

    // Initial array
    fprintf(stdout, "the initial array is: ");
    printv(v, dim);
    fprintf(stdout, "\n\n");

    // Randomize array
    for (x = 0; x < dim; x++) {
        v[x] = rand()%100;
    }

    fprintf(stdout, "the randomized array is: ");
    printv(v, dim);
    fprintf(stdout, "\n\n");

    // Ordering array

    // WARNING: "OVERLAP SECTOR BEGIN"

    args1._v = v;
    args1._x = 0;
    args1._y = dim/4;

    args2._v = v;
    args2._x = dim/4;
    args2._y = dim/2;

    args3._v = v;
    args3._x = dim/2;
    args3._y = (dim/4)*3;

    args4._v = v;
    args4._x = (dim/4)*3;
    args4._y = dim;

    pthread_create(&bot1, NULL, order, &args1);
    pthread_create(&bot2, NULL, order, &args2);
    pthread_create(&bot3, NULL, order, &args3);
    pthread_create(&bot4, NULL, order, &args4);

    pthread_join(bot1, &retval);
    pthread_join(bot2, &retval);
    pthread_join(bot3, &retval);
    pthread_join(bot4, &retval);

    // WARNING: "OVERLAP SECTOR END"

    fprintf(stdout, "the ordered array is: ");
    printv(v, dim);
    fprintf(stdout, "\n\n");

    // End main
    fprintf(stdout, "all done\n");
    return 0;
}

void *order(void *args_ptr ) {

    struct args *a = args_ptr;

    int* v = a->_v;
    int x = a->_x;
    int y = a->_y;

    int i = 0;
    int j = 0;
    int tmp = 0;

    for (i = x; i < y; i++) {
        for (j = x; j < y; j++) {
            if (v[i] < v[j]) {
                tmp=v[i];
                v[i]=v[j];
                v[j]=tmp;
            }
        }
    }

    return 0;
}

void printv (int * v,  int dim) {
    int x = 0;
    for (x = 0; x < dim; x++) {
        fprintf(stdout, "%d ", v[x]);
    }
    fprintf(stdout, "\n\n\n");
    return;
}

编辑：

您提示了错误可能发生的位置，但是 gdb 可以很容易地找到它。如果您按照以下方式进行操作：

$gdb ./prog

然后，在 gdb 内部：

(gdb) run 10000
(gdb) backtrace

应该表明错误发生在pthread_create.c中