leaky.js

var http = require('http');

// good thing we're using the same actual buffer over and over,
// or else this would blow up.  Can you imagine if it was real
// data, and not just the same chunk over and over again?
var chunk = new Buffer(65536);

var server = http.createServer(function(req, res) {
  res.write('start it off...');

  // give the client time to kill the connection,
  // then write a metric ton of junk.
  setTimeout(write, 1000);

  function write() {
    // eat until full
    while (false !== res.write(chunk));

    // eat some more! you're too skinny!
    for (var i = 0; i < 64; i++) {
      res.write(chunk);
    }

    // try again in 100ms
    setTimeout(write, 100);
    setTimeout(checkLeaky, 100);
  }

  function checkLeaky() {
    var l = res.output.map(function(c) {
      return c.length;
    }).reduce(function(a, b) {
      return a + b;
    });
    console.error('leaking: %d', l);
    if (l > 16 * 1024 * 1024) {
      throw new Error('too much leaking!');
    }
  }
});

server.listen(1337, function() {
  var req = http.request({
    port: 1337,
    path: '/',
    method: 'GET'
  });
  req.on('response', function(res) {
    console.error('kill connection');

    // srsly, I'm full, stop.
    res.socket.destroy();

    res.on('end', function() {
      console.error('got end');
      server.close();
    });
  });

  req.end();
});

v0.8.19:

$ ./node leaky.js
kill connection
got end
leaking: 8520850
leaking: 12781275
leaking: 17041700

timers.js:103
            if (!process.listeners('uncaughtException').length) throw e;
                                                                      ^
Error: too much leaking!
    at Object.checkLeaky (/Users/isaacs/node/leaky.js:37:13)
    at Timer.list.ontimeout (timers.js:101:19)

v0.8.20:

$ ./node leaky.js
kill connection
got end

timers.js:103
            if (!process.listeners('uncaughtException').length) throw e;
                                                                      ^
Error: socket hang up
    at createHangUpError (http.js:1360:15)
    at ServerResponse.OutgoingMessage._writeRaw (http.js:507:26)
    at ServerResponse.OutgoingMessage._send (http.js:476:15)
    at ServerResponse.OutgoingMessage.write (http.js:744:12)
    at Object.write [as _onTimeout] (/Users/isaacs/node/leaky.js:17:26)
    at Timer.list.ontimeout (timers.js:101:19)