configurable parallelism

parallelism.js

/**
 * example of configurable parallelism
 */

// silly counter
var i = 0;

// configurable amount of work to run in parallel
var max = 1;

// counts number of active jobs
var running = 0;

// manages amount of running work
function work() {
  while (running < max) {
    ++running
    doStuff();
  }
}

// some worker logic
function doStuff() {
  console.log('I am running %d in parallel (%d)', running, ++i);

  // pretend async call doing i/o or whatever
  async(function(err){
    if (err) {
      // probably stop all work but depends
      return;
    }

    // after the async work is finished, see if we need to do more work
    --running;
    work();
  }
}

work();