linux 多线程锁的问题 trylock得不到锁
如题：
测试代码如下，为何线程一中while的最后不sleep 1s，那么线程2trylock就永远的得不到锁，这个正常吗？

#include <stdio.h>

#include <pthread.h>

 

 

pthread_mutex_t mutex;

pthread_cond_t cond;

int sum = 0;

void *thread1(void *arg)

{

    while(1)

    {

        pthread_mutex_lock(&mutex);

        sum++;

        printf("thread1--->%d\n",sum);

        sleep(3);

        pthread_mutex_unlock(&mutex);

        printf("thread1--->\n");

        printf("thread1--->\n");

        printf("thread1--->\n");

        printf("thread1--->\n");

        printf("thread1--->\n");

        printf("thread1--->\n");

        sleep(1);   /*只有开启睡眠才可以让trylock获得锁*/

    }

}

 

void *thread2(void *arg) 

{

    printf("start thread2....\n");

    while(1)

    {

        int rel = pthread_mutex_trylock(&mutex);

        if(0 == rel)

        {

            sum--;

            printf("thread2-->%d\n",sum);

            pthread_mutex_unlock(&mutex);

        }        

         

    }

}

 

int main() 

{

    printf("test\n");

    sleep(1);

    pthread_t thid1, thid2;    

    printf("condition variable study!\n");

    pthread_mutex_init(&mutex, NULL);

    pthread_cond_init(&cond, NULL);

    pthread_create(&thid1, NULL, (void *) thread1, NULL);

    pthread_create(&thid2, NULL, (void *) thread2, NULL);

     

    pthread_join(thid1,NULL);

    pthread_join(thid2,NULL);

    return 0;

 

}

------解决方案--------------------
没有sleep(1)的话

pthread_mutex_unlock 之后 立即调用 pthread_mutex_lock，
建议thread1里pthread_mutex_unlock之后sched_yield
thread2里pthread_mutex_trylock 改为pthread_mutex_lock
------解决方案--------------------
把        printf("thread1--->\n");
        printf("thread1--->\n");
        printf("thread1--->\n");
  &