/*例子：下面第二次加锁时将出现死锁，如果改为PTHREAD_MUTEX_ERRORCHECK_NP类型，第二次加锁将会返回非零值，不会出现死锁。*/#include <stdlib.h>#include <pthread.h>#include <stdio.h>#include <sched.h>#include <sched.h>void *consumer1(void *p){                 printf("<<<(%u),%d\n", (unsigned)pthread_self(),1);        } void *consumer2(void *p) {                      printf("<<<(%u),%d\n", (unsigned)pthread_self(), 2);                      }int main(int argc, char *argv[]) {pthread_mutex_t mu ;          pthread_t  t1, t2, t3;          int ret;         pthread_mutexattr_t mutexattr;        pthread_mutexattr_init(&mutexattr);         pthread_mutexattr_settype(&mutexattr, PTHREAD_MUTEX_ERRORCHECK_NP);                 pthread_mutex_init(&mu, &mutexattr);        if(!pthread_mutex_lock(&mu))                printf("get mutex (mian)\n");         if(!pthread_mutex_lock(&mu))                  printf("get mutex (main)\n");         ret = pthread_create(&t1, NULL, consumer1, NULL);         ret = pthread_create(&t2, NULL, consumer2,NULL);          if(ret != 0)          {                  printf("create failed,%d\n", ret);                 exit(1);          }                 sleep(2);          printf("main returned\n");       return 0;  } /*注意：PTHREAD_MUTEX_TIMED_NP类型的锁，一个线程加的锁可以被另一个线程解锁，也可以解除未被锁定的锁，不会返回错误。PTHREAD_MUTEX_ERRORCHECK_NP类型的，加锁和解锁要同一个线程，如果某个线程尝试解除锁定的互斥锁不是由该线程锁定或者未锁定，则将返回错误。*/