node/test/parallel/test-http-max-sockets.js

// Copyright Joyent, Inc. and other Node contributors.
//
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// following conditions:
//
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// in all copies or substantial portions of the Software.
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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'use strict';
require('../common');

// Make sure http server doesn't wait for socket pool to establish connections
// https://github.com/nodejs/node-v0.x-archive/issues/877

const http = require('http');
const assert = require('assert');

const N = 20;
let responses = 0;
let maxQueued = 0;

const agent = http.globalAgent;
agent.maxSockets = 10;

const server = http.createServer(function(req, res) {
  res.writeHead(200);
  res.end('Hello World\n');
});

server.listen(0, '127.0.0.1', function() {
  const { port } = server.address();
  const addrString = agent.getName({ host: '127.0.0.1', port });

  for (let i = 0; i < N; i++) {
    const options = {
      host: '127.0.0.1',
      port
    };

    const req = http.get(options, function(res) {
      if (++responses === N) {
        server.close();
      }
      res.resume();
    });

    assert.strictEqual(req.agent, agent);

    console.log(
      `Socket: ${agent.sockets[addrString].length}/${
        agent.maxSockets} queued: ${
        agent.requests[addrString] ? agent.requests[addrString].length : 0}`);

    const agentRequests = agent.requests[addrString] ?
      agent.requests[addrString].length : 0;

    if (maxQueued < agentRequests) {
      maxQueued = agentRequests;
    }
  }
});

process.on('exit', function() {
  assert.strictEqual(responses, N);
  assert.ok(maxQueued <= 10);
});