Node.js Multithreading Child Process
Example
Child Processes are the way to go when one wants to run processes independently with different initialization and concerns. Like forks in clusters, a child_process runs in its thread, but unlike forks, it has a way to communicate with its parent.
The communication goes both ways, so parent and child can listen for messages and send messages.
Parent (../parent.js)
var child_process = require('child_process');
console.log('[Parent]', 'initalize');
var child1 = child_process.fork(__dirname + '/child');
child1.on('message', function(msg) {
console.log('[Parent]', 'Answer from child: ', msg);
});
// one can send as many messages as one want
child1.send('Hello'); // Hello to you too :)
child1.send('Hello'); // Hello to you too :)
// one can also have multiple children
var child2 = child_process.fork(__dirname + '/child');
Child (../child.js)
// here would one initialize this child
// this will be executed only once
console.log('[Child]', 'initalize');
// here one listens for new tasks from the parent
process.on('message', function(messageFromParent) {
//do some intense work here
console.log('[Child]', 'Child doing some intense work');
if(messageFromParent == 'Hello') process.send('Hello to you too :)');
else process.send('what?');
})
Next to message one can listen to many events like 'error', 'connected' or 'disconnect'.
Starting a child process has a certain cost associated with it. One would want to spawn as few of them as possible.
