Drop-in Replacement for fs to prevent too many open files

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2850.5.011 years ago11 years agoMinified + gzip package size for filequeue in KB



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

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.


Through NPM
$ npm install filequeue

or using Git
$ git clone git:// node_modules/filequeue/

How to Use

Instantiate Filequeue with a maximim 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) unless the `newQueue` is explicitly passed.

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

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

Use any of the following supported fs methods

  • readFile
  • writeFile
  • readdir
  • stat
  • exists

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

Other Methods

Pull requests to add other fs methods are welcome - these are the methods I use most often, so I built in support for them.