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In Process
Thijser
Asked: 2016-04-27 02:01:16 +0800 CST

How to kill proccess that spawns several java programs that each take a port

  • 772

I have a program .sh that spawns several child proces like so: 

javac *.java
rmiregistry 3300 & 
sleep 5
java Node 3300 3001 1 &
sleep 1
java Node 3300 3002 1 &
sleep 1
java Node 3300 3003 1 &
sleep 1
java Node 3300 3004 1 &
sleep 1
java Node 3300 3005 1 &

Now When I run this in a terminal screen I would like to be able to do something like ctr-c to stop this. However when I do it does not release the ports taken by the Nodes. Is there any way to make sure that when I ctr-c the ports are unbound or is there a shortkey that also frees up the ports used by the child processes? Or do I have to use a separate kill command? Also note that the nodes can and do launch multiple threads themselves (from within java).

java

2 Answers

  1. The way to kill all the jobs launched by a process is to use the process group ID (pgid). The simplest way to see that it to launch your script in the background:

    $ launch_java.sh &
[1] 25649

    The number printed above is the PID of the launch_java.sh which is also the group ID since that launches the rest. Alternatively, you can find it through ps:

    $ ps -a -o pgid,command | grep java
25649 java Node 3300 3002 1

    The 1st field is the pgid. Once you have that, you can use kill to kill it and all its children:

    kill -TERM -25649

    As explained in man kill:

              -n     where n is larger than 1.  All processes in process group
                 n are signaled.  When an argument of  the  form  '-n'  is
                 given,  and it is meant to denote a process group, either
                 a signal must be specified first, or the argument must be
                 preceded  by a '--' option, otherwise it will be taken as
                 the signal to send.
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  2. use ps -aef or ps -aux command to find PID of parent of children and kill it by kill -9 PID .

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