Killing a bash script does not kill child processes

Question

I have written a test script which runs another script to start the server to test. When the tests have completed a SIGKILL message is sent to the server process, however when running the test script again the server throws a EADDRINUSE error (I‘m in a node.js environment) which means the port the server is trying to mount to is currently in use. The process we tried to kill with a SIGKILL is still running. I don‘t believe this is a node specific issue, but rather a lack of education on my end for how bash processes work.

Here are some specifics, this is my start script called scripts/start-node.sh:

#!/bin/bash

node_modules/.bin/babel-node --stage 0 index.js

This is my node server called index.js (I haven‘t authored any process event listeners):

Http.createServer(…).listen(PORT, () => console.log(`Server listening on ${PORT}`))

And the start script is controlled with the node child_process module:

var child = child_process.spawn('scripts/start-node.sh')
// Later…
child.kill('SIGKILL')

Answer 1

To kill a child process and all it's children you may use process.kill with a negative pid (to kill a process group)

var child = child_process.spawn('scripts/start-node.sh', {detached: true})
// Later…
process.kill(-child.pid, 'SIGKILL');

See details on child_process documentation for options.detached

On non-Windows, if the detached option is set, the child process will be made the leader of a new process group and session.

Referencing here a portion of man 2 kill for some details:

If pid is less than -1, then sig is sent to every process in the process group whose ID is -pid.

---

Another option may be using trap in your shell script to intercept a signal and kill all the children and using child.kill('SIGTERM') from node (as SIGKILL will not be intercepted by trap)

#!/bin/bash

trap 'kill $(jobs -p)' EXIT
node_modules/.bin/babel-node --stage 0 index.js

Answer 2

Simply:

#!/bin/bash
if pgrep -x "node" > /dev/null
then
mv -f  /usr/local/bin/node /usr/local/bin/node.1
killall  node
mv -f /usr/local/bin/node.1 /usr/local/bin/node
which node
else
echo "process node not exists"
fi

node is creating child process every-time we kill it. So it's not possible to kill the process from kill,pkill or killall commands. So we are removing node command to make forking process fail and then we kill the process.Finally we restore the node command.

Answer 3

have a handler for process signals in your server

server.js

 var http = require('http');

function handleRequest(request, response){
    response.end("Hello");
}
var server = http.createServer(handleRequest);

server.listen(3000, function(){console.log("listening...")});
process.title="testserver"

process.on('SIGQUIT', function() {
  server.close()
});

startup.sh

 #!/bin/bash
 node server.js & echo "started"

and then have a "shutdown.sh".

shutdown.sh

#!/bin/bash
pkill -QUIT testserver & echo "stoped"

It will kill all processes with that name, in case you are spawning multible processes in your "start-node.sh". This way you can have some clean-up code when shutting down e.g. closing all connections etc.

and in your test runner you can do

var exec = require('child_process').exec;
exec("./start.sh")
// later...
exec("./stop.sh")