Node background worker possible?

[Johan Alkstål]

I'm building a sports app with a game simulation engine.

I'd like the simulation engine to run independently of the main web app.

Questions I have are,

do I need to run it independently first of all, in order to not cause performance problems with the main web app?

Is it possible to have a node app running like a worker in the background?

Anyone with any other ideas on how to set this up using Node?

[Ryan Dahl]

Yeah, forking off a separate process is a good idea. Check out require('child_process').fork() which will allow you to send messages back and forth between the web-head and the simulator

http://nodejs.org/api/child_process.html#child_process_child_process_fork_modulepath_args_options

[Akzhan Abdulin]

Yet another option is require('webworker'). Typical implementation is https://npmjs.org/package/webworker-threads

2014/1/3 Johan Alkstål <johan....@gmail.com>

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[Johan Alkstål]

So should this forked child process always be running (and thus having all simulations use it) or should I fork one for each simulation run?

I mean if the simulations should be queued and executed in order or in parallel by multiple processes?

And what are the benefits/drawbacks from using the web worker implementation with multiple threads?

[Ryan Dahl]

On Fri, Jan 3, 2014 at 1:47 PM, Johan Alkstål <johan....@gmail.com> wrote:

So should this forked child process always be running (and thus having all simulations use it) or should I fork one for each simulation run?

I mean if the simulations should be queued and executed in order or in parallel by multiple processes?

  

That'll depend on how long these simulations run and how many of them there will be - but I would suspect you want on child process per simulation.

 

And what are the benefits/drawbacks from using the web worker implementation with multiple threads?

Web worker is just a different (browser compatible) API for child_process.fork. Probably you should just use the API node provides unless you're thinking about running these simulations client side as well.

[Hongli Lai]

On Friday, January 3, 2014 8:14:51 PM UTC+1, Ryan Dahl wrote:

On Fri, Jan 3, 2014 at 1:47 PM, Johan Alkstål <johan....@gmail.com> wrote:

So should this forked child process always be running (and thus having all simulations use it) or should I fork one for each simulation run?

I mean if the simulations should be queued and executed in order or in parallel by multiple processes?

  

That'll depend on how long these simulations run and how many of them there will be - but I would suspect you want on child process per simulation.

It also depends on how expensive the startup of your code is. If it takes 5 seconds to start your simulation program then you should not create a process per simulation. Instead, you should keep the simulation program running and feed it input to avoid the startup cost.

[Johan Alkstål]

Thank you all for your replies! Much appreciated.

2014/1/4 Hongli Lai <hong...@gmail.com>

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[Tony Huang]

i think use "forever" instead of raw child process may be a good idea~

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[Johan Alkstål]

Tony, what do you mean?

2014/1/5 Tony Huang <cnw...@gmail.com>

[Hongli Lai]

Forever is a tool for running node processes in the background and keeping them running. It eases the management of processes somewhat.

Sent from my Android phone.

[John Engstrom]

.p....pp

[Johan Alkstål]

Wouldn't that still be using child processes or would it be a completely different node app?

2014/1/5 Hongli Lai <hon...@phusion.nl>

[Hongli Lai]

Yes it would still use child processes. It's essentially the same thing, just with easier management.

Sent from my Android phone.