Filequeue

Drop-in Replacement for fs that avoids Error: EMFILE, too many open files.

As of version 0.4.0, Filequeue supports Node 0.10.x, and as of version 0.5.0, it has basic Streams support.

Filequeue was born out of my encounter with Error: EMFILE, too many open files, which occurs when you try to open too many files at once on your system. Due to Node's asynchronous nature, if you perform a lot of fs.readFile or similar operations in quick succession, you can easily hit your system's maxfiles limit, usually set to 256 on a dev box.

Filequeue creates a replacement for fs, that I use as fq with many of the same operations. However, it keeps track of how many files are open at once, and queues them if there are too many.

Installation

Through NPM

$ npm install filequeue

or using Git

$ git clone git://github.com/treygriffith/filequeue.git node_modules/filequeue/

How to Use

Instantiate Filequeue with a maximum number of files to be opened at once (default is 200)

  var FileQueue = require('filequeue');
  var fq = new FileQueue(100);

  // additional instances will attempt to use the same instance (and therefore the same maxfiles)

  var FileQueue2 = require('filequeue');
  var fq2 = new FileQueue2(100);

  console.log(fq === fq2); // => true

  // you can force a new instance of filequeue with the `newQueue` parameter

  var fq3 = new FileQueue(100, true);

  console.log(fq === fq3); // => false

Use any of the following supported fs methods

• readFile
• writeFile
• readdir
• rename
• symlink
• mkdir
• stat
• exists
• createReadStream
• createWriteStream

  for(var i=0; i<1000; i++) {
    fq.readFile('/somefile.txt', {encoding: 'utf8'}, function(err, somefile) {
      console.log("data from somefile.txt without crashing!", somefile);
    });
  }

Other Methods

Adding a new fs method is simple, just add it to the methods.js file following the conventions therein.

Pull requests to add other fs methods with tests exercising them are welcome.