fixed.js

var http = require('http');
var Readable = require('stream').Readable;

http.createServer(function(req, res){
  
  var stream = Readable();
  
  stream._read = function(){
    console.log('_read', Date.now());
    if (stream.closed) return stream.push(null);
    setTimeout(function(){
      stream.push(Date.now()+'\n');
    }, 100);
  };
  
  stream.close = function(){
    console.log('close');
    stream.closed = true;
  };
  
  req.on('close', function(){
    stream.close();
  });
  
  stream.pipe(res);
  
}).listen(3000);

leaks.js

var http = require('http');
var Readable = require('stream').Readable;

http.createServer(function(req, res){
  
  var stream = Readable();
  
  stream._read = function(){
    console.log('_read', Date.now());
    setTimeout(function(){
      stream.push(Date.now()+'\n');
    }, 100);
  };

  stream.pipe(res);
  
}).listen(3000);

problem.md

Readable stream cleanup issues.

Steps to reproduce:

1. Run node leaks.js
2. Issue a request to it, for example via curl http://localhost:3000
3. Watch leaks.js repeatedly print _read <Date> to the console while the request is active
4. Kill the request by killing curl
5. leaks.js still keeps printing _read <Date>. The readable stream is still being read although the request ended

Fixed in fixed.js by implementing and calling a custom closing mechanism. The fact that we have to call the .close() manually means that if you just fs.createReadStream("/dev/random").pipe(res) you create a leak again.

Same in node 0.10 and 0.11.