Phantomjs works but is very slow

问题:

I am trying to take a screenshot of a webpage with PhantomJS. Specifically, I am using the example of capturing espn.com from this example. My code looks like this:

var page = new WebPage(); 
    page.open('http://www.espn.com', function (status) {
    page.render('fb.png');
    phantom.exit();
});

I then go to my PhantomJS directory with either my terminal or command prompt and run:

phantomjs shotty.js

Everything runs great, however it takes 6-8 seconds to complete the output image. Is that normal? Is there a faster way to accomplish this so that it completes in a second or less?

I am using CentOS and Windows 7. Both boxes have 8GB of RAM, 3.2 GHz CPU, and I'm getting 22Mbp/s down and 1Mbp/s up on speedtest.net

回答1:

Yes this is normal. When you attempt to render, PhantonJS will still wait for the page.open event to fire the load event to signify that the entire DOM has been loaded.

Take a look at what happens when I load espn.com locally on my system. It takes ~2 seconds for DOMContentLoaded to finish, and then ~7 seconds for the ready event to fire.

回答2:

Well, in my case, the page was waiting for some GET requests and was not able to reach the requests' server and it kept waiting for long. I could only figure it out when i used the remote debugger option.

phantomjs --remote-debugger-port=9000 loadspeed.js <some_url>

and inside the loadspeed.js file

page.onResourceRequested = function (req) {
    console.log('requested: ' + JSON.stringify(req, undefined, 4));
};

page.onResourceReceived = function (res) {
    console.log('received: ' + JSON.stringify(res, undefined, 4));
};

and then loading localhost:9000 in any webkit browser (safari/chrome) and seeing the console logs where i could figure out it was waiting for some unreachable requests for a long time.

TO BYPASS THIS - REDUCE THE TIMEOUT:

page.settings.resourceTimeout = 3000; //in milliseconds

and things were very quick after that. Hope this helps

回答3:

I didn't thought that the following would work but for me it did (on Windows):

open Internet Explorer > Internet Options > Connections > LAN Settings and disable the "Automatically detect settings"

original Post: https://plus.google.com/+MatthiasG%C3%B6tzke/posts/9v9BMCJj2k6