exec-queue/redo.js

Safely run exec in a loop.

const MAX_PROCS = 10;

var exec = require('child_process').exec;
var queue = [];

function nextInLine () {
  console.log('queue length: ', queue.length);
  if (queue.length > 0) {
    var args = queue.shift();
    exec.apply(null, args);
  }
};

module.exports = function () {
  var args = Array.prototype.slice.call(arguments);
  var oldCb = args.pop();
  args.push(function () {
    oldCb.apply(null, arguments);
    nextInLine(); // deque
  });
  queue.push(args); // enque
  if (queue.length < MAX_PROCS) {
    process.nextTick(function () {
      nextInLine();
    });
  }
};