puppeteer-browser-pool.js

/**
 * Copyright 2018 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @author rahulkumar66@ (Rahul Kumar)
 */

/**
* Demonstrates how to reuse browser instances across multiple tasks
* resulting in improved load times for subsequent requests.
* This has huge load time improvements in case of SPAs
*/

const genericPool = require('generic-pool');
const puppeteer = require('puppeteer');

const VIEWPORT = {width: 1028, height: 800, deviceScaleFactor: 2};
const HACKER_NEWS_URL = 'https://hn.algolia.com/';
const HACKER_NEWS_QUERY_URL = `${HACKER_NEWS_URL}?query=chrome`;

const browserPoolFactory = {
  create: async () => {
    const browser = await puppeteer.launch({headless: false});
    const page = await browser.newPage();
    return page;
  },
  destroy: (browser) => {
    return browser.close();
  },
};

const browserPool = genericPool.createPool(browserPoolFactory, {
  max: 5, // maximum number of browser instances that can be created at any given time 
  min: 2, // minimum number of browser instances to keep in pool at any given time
  maxWaitingClients: 50
});

async function getContent(url) {
  const page = await browserPool.acquire();
  await page.setViewport(VIEWPORT);

  const response = await page.goto(url, {waitUntil: 'networkidle2', timeout: 60000});
  // release browser instance back to pool so it can be reused
  await browserPool.release(page);
  return response.text();
}

(async () => {
  const responseHackerNews = await getContent(HACKER_NEWS_URL);
  console.log(responseHackerNews);

  // this request will use the instance from the current browser pool resulting in faster response
  const responseHackerNewsWithQuery = await getContent(HACKER_NEWS_QUERY_URL);
  console.log(responseHackerNewsWithQuery);
})();