写个函数来解决多线程同时读写一个文件的问题

 <?php
      $fp = fopen("/tmp/lock.txt","w+");
      if(flock($fp, LOCK_EX)){// 进行排它型锁定
          fwrite($fp,"Write something here\n");
          flock($fp, LOCK_UN);// 释放锁定
      }else{
          echo "Couldn't lock the file !";
      }
      fclose($fp);
 ?>