How to send consecutive requests with HTTP keep-alive in node.js?

Question

I'm using node.js 0.6.18, and the following code makes node.js close the TCP connection between every two requests (verified with strace on Linux). How do I make node.js reuse the same TCP connection for multiple HTTP requests (i.e. keep-alive)? Please note that the webserver is capable of keep-alive, it works with other clients. The webserver returns a chunked HTTP response.

var http = require('http');
var cookie = 'FOO=bar';
function work() {
  var options = {
      host: '127.0.0.1',
      port: 3333,
      path: '/',
      method: 'GET',
      headers: {Cookie: cookie},
  };
  process.stderr.write('.')
  var req = http.request(options, function(res) {
    if (res.statusCode != 200) {
      console.log('STATUS: ' + res.statusCode);
      console.log('HEADERS: ' + JSON.stringify(res.headers));
      process.exit(1)
    }
    res.setEncoding('utf8');
    res.on('data', function (chunk) {});
    res.on('end', function () { work(); });
  });
  req.on('error', function(e) {
    console.log('problem with request: ' + e.message);
    process.exit(1);
  });
  req.end();
}
work()

Answer 1

I was able to get this to work (verified with strace) by creating an http.Agent and setting its maxSockets property to 1. I don't know if this is the ideal way to do it; however, it does meet the requirements. One thing that I did notice is that what the docs claimed about http.Agent behavior did not accurately describe how it worked in practice. Code below:

var http = require('http');
var cookie = 'FOO=bar';
var agent = new http.Agent;
agent.maxSockets = 1;

function work() {
  var options = {
      host: '127.0.0.1',
      port: 3000,
      path: '/',
      method: 'GET',
      headers: {Cookie: cookie},
      agent: agent
  };
  process.stderr.write('.')
  var req = http.request(options, function(res) {
    if (res.statusCode != 200) {
      console.log('STATUS: ' + res.statusCode);
      console.log('HEADERS: ' + JSON.stringify(res.headers));
      process.exit(1)
    }
    res.setEncoding('utf8');
    res.on('data', function (chunk) {});
    res.on('end', function () { work(); });
  });
  req.on('error', function(e) {
    console.log('problem with request: ' + e.message);
    process.exit(1);
  });
  req.end();
}
work()

EDIT: I should add that I did my testing with node.js v0.8.7

Answer 2

you can just set:

http.globalAgent.keepAlive = true