1 读写锁定义

  读写锁适用于多个读,单个或者少量写操作,它是一种特别的互斥锁;

2 示例代码如下:

多线程&读写锁问题

 

 

3 说明:

  3.1 写锁锁定时,其他所有读写操作,必须等待;

    上图中的30行打开时候,输出如下,全部处于等待阶段;

      in readThread:139786146199296
      in readThread:139786154592000
      in readThread:139786137806592
      in writeThread:139786121021184
      in readThread:139786129413888

  3.2 读锁,其他读操作不影响,但是写操作等待;

    上图31行打开,输出如下,读操作不受影响,写操作等待;

      in readThread:139932255573760
      in readThread:139932238788352
      tid is: -2090682624, read
      in readThread:139932247181056
      tid is: -2082289920, read
      tid is: -2073897216, read
      in readThread:139932230395648
      tid is: -2099075328, read
      in writeThread:139932222002944

  3.3 非阻塞式读写锁;

    使用pthread_rwlock_tryrdlock代替12行pthread_rwlock_rdlock,不会进行阻塞,但是会返回错误码;

    

 

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