c/c++语言开发共享C语言多线程开发中死锁与读写锁问题详解

//多线程多锁，抢占锁资源  #include <stdio.h>  #include <pthread.h>  #include <unistd.h>  // 创建2个互斥量  pthread_mutex_t mutex1, mutex2;  void * worka(void * arg) {      pthread_mutex_lock(&mutex1);      sleep(1);      pthread_mutex_lock(&mutex2);      printf("worka....n");      pthread_mutex_unlock(&mutex2);      pthread_mutex_unlock(&mutex1);      return null;  }  void * workb(void * arg) {      pthread_mutex_lock(&mutex2);      sleep(1);      pthread_mutex_lock(&mutex1);      printf("workb....n");      pthread_mutex_unlock(&mutex1);      pthread_mutex_unlock(&mutex2);      return null;  }  int main() {      // 初始化互斥量      pthread_mutex_init(&mutex1, null);      pthread_mutex_init(&mutex2, null);      // 创建2个子线程      pthread_t tid1, tid2;      pthread_create(&tid1, null, worka, null);      pthread_create(&tid2, null, workb, null);      // 回收子线程资源      pthread_join(tid1, null);      pthread_join(tid2, null);      // 释放互斥量资源      pthread_mutex_destroy(&mutex1);      pthread_mutex_destroy(&mutex2);      return 0;  }

/*      读写锁的类型 pthread_rwlock_t      int pthread_rwlock_init(pthread_rwlock_t *restrict rwlock, const pthread_rwlockattr_t *restrict attr);      int pthread_rwlock_destroy(pthread_rwlock_t *rwlock);      int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock);      int pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock);      int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);      int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);      int pthread_rwlock_unlock(pthread_rwlock_t *rwlock);      案例：8个线程操作同一个全局变量。      3个线程不定时写这个全局变量，5个线程不定时的读这个全局变量  */  #include <stdio.h>  #include <pthread.h>  #include <unistd.h>  // 创建一个共享数据  int num = 1;  // pthread_mutex_t mutex;  pthread_rwlock_t rwlock;  void * writenum(void * arg) {      while(1) {          pthread_rwlock_wrlock(&rwlock);          num++;          printf("++write, tid : %ld, num : %dn", pthread_self(), num);          pthread_rwlock_unlock(&rwlock);          usleep(100);      }      return null;  }  void * readnum(void * arg) {      while(1) {          pthread_rwlock_rdlock(&rwlock);           printf("===read, tid : %ld, num : %dn", pthread_self(), num);          pthread_rwlock_unlock(&rwlock);          usleep(100);      }      return null;  }  int main() {     pthread_rwlock_init(&rwlock, null);      // 创建3个写线程，5个读线程      pthread_t wtids[3], rtids[5];      for(int i = 0; i < 3; i++) {          pthread_create(&wtids[i], null, writenum, null);      }      for(int i = 0; i < 5; i++) {          pthread_create(&rtids[i], null, readnum, null);      }      // 设置线程分离      for(int i = 0; i < 3; i++) {         pthread_detach(wtids[i]);      }      for(int i = 0; i < 5; i++) {           pthread_detach(rtids[i]);      }      pthread_exit(null);      pthread_rwlock_destroy(&rwlock);      return 0;  }