问题一：如何kill掉defunct进程
资料说defunct进程是父进程先于子进程退出而导致的，那么kill defunct进程的父进程就可以解决defunct进程了。方法如下：ps -ef|grep defunct 显示defunct进程列表，其中第三项即是PPID，父进程的PID。
另外附上查询结果每列的含义：
-f Display the uid, pid, parent pid, recent CPU usage, process start time, controling tty, elapsed CPU usage, and the associated command. If the -u option is also used, display the user name rather than the numeric uid. When -o or -O is used to add to the display following -f, the command field is not truncated as severely as it is in other formats.