[juliantec_list] Re:多线程互斥问题
- From: "J.evan" <free123ba@xxxxxxx>
- To: "Linux Xp" <xp2linux@xxxxxxxx>
- Date: Wed, 28 Dec 2011 11:49:08 +0800 (CST)
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
<===是线程执行顺序
for(i = 0; i < l; i++)
{
pthread_join(tid[i], NULL);
}
这儿并不能确定线程的运行顺序，
pthread_mutex_unlock(&lock1);
if(number != 0)
{
if(isPrimeLL(number))
{
pthread_mutex_lock(&lock2);
这之间可能会出现线程切换
我修改了下，没有测试，你自己测试下。看看能否解决段错误的问题。
void *finder()
{
long long number;
while(1)
{
pthread_mutex_lock(&lock1);
number = getNumber();
if( number == 0){
pthread_mutex_unlock(&lock1);
pthread_exit(NULL);
}
if(isPrimeLL(number))
{
archive[primes_found] = number;
primes_found++;
}
pthread_mutex_unlock(&lock1);
}
}
在 2011-12-28 11:28:29，"Linux Xp" <xp2linux@xxxxxxxx> 写道：
>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;
>}
>
>Learning, Just As Your Favourite Thing!
>
>Maillist, See http://www.juliantec.info/mlist/mail-lists.html
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>
>
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