Simple Process Manager (SPaM)

SPAM is a module for simple node.js process management, and wraps the cluster module. It has nothing to do with email spam.

Use

Yarn is recommended as a package manager, but npm can be used as an alternative.

To install:

# install yarn if required
npm install -g yarn
yarn add spam

To create some processes, using the spawn method. This takes the following parameters:

• Configuration object
  • number (number of processes to spawn, e.g. 4)
  • timeout (time in milliseconds to allow each spawn to occur, before timing out)
  • strategy (either 'series', or 'parallel', to spawn one at a time, or all together)
  • readyOn (what signal indicates the script is ready, 'ready' or 'listening' - default)
• Callback when initialization of the module is complete

var spam = require('spam');

// to create 4 processes using the myscript.js script - ready on listen(),
// created in parallel, with a timeout of 60 seconds
spam.setScript('./myscript.js');
spam.spawn(
  {
    number: 4,
    timeout: 60000,
    strategy: 'parallel'
  }, function(err) {
      // callback occurs when all processes have declared they are working
      // or a timeout occurs
      if (err) {
        console.log('oops');
      }
});

// to create 2 processes callback is called when 'ready' message sent, not on 'listen'
// created in series, with no timeout
spam.spawn(
  {
    number: 2,
    timeout: 0,
    strategy: 'serial',
    readyOn: 'ready'
  },  function(err) {
      // callback occurs when all processes have declared they are working
      // or a timeout occurs
      if (err) {
        console.log('oops');
      }
});

If you want to log what's going on in SPAM

spam.on('log', function(message) {
  // do some logging
  console.log('SPAM: ' + message);
});

If you want to gracefully restart all the processes, by starting a new worker before killing the old worker, do this with the restart method.

// graceful restart of all the processes
spam.restart({ strategy: 'series' }, function(err) {
  if (err) {
    console.log('oops');
  }
});

To stop all the processes:

// stop all
spam.stop(function() {
  console.log('stop initiated')
});

NOTE: The scripts that are run, either need to run server.listen() or emit a specific 'ready' message. If they do not do this, then SPAM will assume they've not started and time them out. You can emit a 'ready' message using a convenience function or explicitly using process.send();

// using the signal module
var signal = require('spam').signal;
signal.ready();

// using the process.send method
process.send({ cmd: 'ready'});

Tests

To run the npm unit tests, install development dependencies and run tests with 'npm test' or 'make'.

# clone repo and install dependencies
git clone [email protected]:iandotkelly/spam.git
cd spam
yarn
# run tests
yarn test

Coverage can be measured after running the tests, and an html coverage report is written in the coverage/lcov-report directory:

open coverage/lcov-report/index.html

If you contribute to the project, tests are written in mocha, using should.js or the node.js assert module.