[juliantec_list] 多线程互斥问题
- From: Linux Xp <xp2linux@xxxxxxxx>
- To: "app-dev-in-linux@xxxxxxxxxxxxxx" <app-dev-in-linux@xxxxxxxxxxxxxx>
- Date: Wed, 28 Dec 2011 11:28:29 +0800 (CST)
Hi:
我在写一个寻找素数的多线程程序，
但是几次下来程序的执行结果不完全一样，
并且偶尔会出现段错误，不知道是什么问题。
我程序的思路是这样的：
1，通过命令行指定从哪里开始查找素数，并
指定需要查找多少个素数。
2，另外通过命令行参数来指定需要多少个线
程参与素数的查找。
下面是我的部分程序代码。
其中 isPrimeLL 是判断是否为素数的函数，
在另外一个静态库里面。
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
void *finder();
void *waiter_proc();
long long getNumber();
int isPrimeLL(long long n);
// global variables
long long n, *archive;
int m, l, primes_found = 0;
pthread_t *tid;
pthread_t waiter;
pthread_mutex_t lock1 = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t lock2 = PTHREAD_MUTEX_INITIALIZER;
int main(int argc, char *argv[])
{
long i = 0;
if(argc != 4)
{
fprintf(stderr,
"Usage: %s <starting number> <# of primes> <# of threads>\n",
argv[0]);
return 1;
}
// starting num
n = atoll(argv[1]);
// number of primes to find
m = atoi(argv[2]);
archive = malloc(m * sizeof(long long));
// numbers of thread
l = atoi(argv[3]);
tid = malloc(l * sizeof(pthread_t));
for(i = 0; i < l; i++)
{
if(pthread_create(&tid[i], NULL, finder, NULL))
return 1;
}
// waiter thread
if(pthread_create(&waiter, NULL, waiter_proc, NULL))
return 1;
// wait for waiter thread to exit
pthread_join(waiter, NULL);
for(i = 0; i < m; i++)
{
printf("%llu\n", archive[i]);
}
free(archive);
free(tid);
return 0;
}
void *finder()
{
long long number;
while(1)
{
pthread_mutex_lock(&lock1);
number = getNumber();
pthread_mutex_unlock(&lock1);
if(number != 0)
{
if(isPrimeLL(number))
{
pthread_mutex_lock(&lock2);
archive[primes_found] = number;
primes_found++;
pthread_mutex_unlock(&lock2);
}
}
else
{
pthread_exit(NULL);
}
}
}
void *waiter_proc()
{
int i;
// wait for finder threads to exit
for(i = 0; i < l; i++)
{
pthread_join(tid[i], NULL);
}
}
long long getNumber()
{
if(primes_found < m)
{
return n++;
}
else
return 0;
}
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