以下程序因分段错误而停止。当我尝试调试它时,显示
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff6ff4700 (LWP 7293)]
0x0000000000400a79 in do_work(void*) ()
(gdb) bt
#0 0x0000000000400a79 in do_work(void*) ()
#1 0x00007ffff7bc4182 in start_thread (arg=0x7ffff6ff4700)
at pthread_create.c:312
#2 0x00007ffff78f0fbd in clone ()
at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
该计划如下:
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <cstring>
#include <unistd.h>
#include <ctime>
#define NTHREADS 3
#define iter 10
#define max_key 3
pthread_mutex_t lock[max_key];
void *do_work(void *tid)
{
int i, start, *mytid, end,rank,len,key;
double lock_var;
mytid = (int *) tid; //edit: suggested by Eric Tsui; It fixed the problem
for (i=0; i<iter; i++){
lock_var=(double)rand() / (double)RAND_MAX ;
if (lock_var<=0.5){
key = 0;
}
else if ((lock_var>0.5)&&(lock_var<=0.9)){
key = 1;
}
else {
key = 2;
}
pthread_mutex_lock (&lock[key]);
printf("I'm:%d with key:%d\n",*mytid,key);
sleep(1);
pthread_mutex_unlock (&lock[key]);
}
pthread_exit(NULL);
}
int main(int argc, char *argv[])
{
int i, start, tids[NTHREADS];
pthread_t threads[NTHREADS];
pthread_attr_t attr;
srand(time(NULL));
for (i=0;i<max_key;i++){
pthread_mutex_init(&lock[i], NULL);
}
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
for (i=0; i<NTHREADS; i++) {
tids[i] = i;
pthread_create(&threads[i], &attr, do_work, (void *) &tids[i]);
}
for (i=0; i<NTHREADS; i++) {
pthread_join(threads[i], NULL);
}
printf ("Done\n");
pthread_attr_destroy(&attr);
for (i=0;i<max_key;i++){
pthread_mutex_destroy(&lock[i]);
}
pthread_exit (NULL);
}
我检查了代码但无法找到分段错误的原因。 有谁能请让我知道此代码中分段错误背后的原因。
答案 0 :(得分:1)
myid
func中的do_work
应该分配输入tid
,
void *do_work(void *tid)
{
int i, start, *mytid, end,rank,len,key;
double lock_var;
mytid = (int *) tid; //edit: suggested by Eric Tsui; It fixed the problem
for (i=0; i<iter; i++){
lock_var=(double)rand() / (double)RAND_MAX ;
if (lock_var<=0.5){
key = 0;
}
else if ((lock_var>0.5)&&(lock_var<=0.9)){
key = 1;
}
else {
key = 2;
}
pthread_mutex_lock (&lock[key]);
printf("I'm:%d with key:%d\n",*mytid,key);
sleep(1);
pthread_mutex_unlock (&lock[key]);
}
pthread_exit(NULL);
}