Rendering to stdout fails

[slorber]

var page = require('webpage').create();
page.viewportSize = { width: 1200, height: 800 };



page.open('http://localhost:3000/', function() {

  setInterval(function() {
    page.render("/dev/stdout");
    page.render("test2.png");
    phantom.exit()
  }, 5000);

});

I run phantomjs recorder.js >> test.png

This works with 1.9.7
This does not work with 2.1.1

In 2.1.1, test.png remains empty while content was expected

[slorber]

Sorry, I'm not sure what is happening, it seems it has worked but not anymore...

sebastien@sebastien-xps:todomvc (master *%)$ node -v
v4.2.3
sebastien@sebastien-xps:todomvc (master *%)$ npm -v
2.14.7
sebastien@sebastien-xps:todomvc (master *%)$ phantomjs -v
2.1.1

I'm running

var page = require('webpage').create();
var fs = require("fs");

page.viewportSize = { width: 1200, height: 800 };

page.open('http://localhost:3000/', function() {

  setInterval(function() {
    fs.write("/dev/stdout", page.renderBase64(), "w");
  }, 1000);

});

sebastien@sebastien-xps:todomvc (master *%)$ phantomjs recorder.js
Unable to open file '/dev/stdout'

  phantomjs://platform/fs.js:79 in open
  phantomjs://platform/fs.js:136 in write
  phantomjs://code/recorder.js:13
Unable to open file '/dev/stdout'

  phantomjs://platform/fs.js:79 in open
  phantomjs://platform/fs.js:136 in write
  phantomjs://code/recorder.js:13
Unable to open file '/dev/stdout'

  phantomjs://platform/fs.js:79 in open
  phantomjs://platform/fs.js:136 in write
  phantomjs://code/recorder.js:13
PhantomJS has crashed. Please read the bug reporting guide at
<http://phantomjs.org/bug-reporting.html> and file a bug report.

[slorber]

Sorry I don't really understand what is happening there.

It seems to fail when I install phantomjs with npm install phantomjs -g, but it works when I install it with sudo apt-get install phantomjs.

Note that I tried to launch phantomjs with sudo and did not work better. I also used in both cases the 1.9.0 version which is available on apt-get and npm, and got different results.

Any idea why it fails when installed through npm (on ubuntu?). It was the case on my laptop, and on a remote server running a more recent version of ubuntu.

[ariya]

The report is a bit confusing. I think you need to summarize it again so we all can understand clearly in which situation(s) the rendering does not as expected. In each situation, please provide the information on:

• the PhantomJS version: phantomjs --version
• the system information: uname -a
• OS details and version: lsb_release -a

Also, if possible, eliminate the case where you install PhantomJS via npm because we do not own or control that module. You have to bring up any problem with npm package to https://github.com/Medium/phantomjs.

Thank you!

[slorber]

@ariya to sum it up, I don't exactly know what happens, but here are some insights:

Script to run: recorder.js

var page = require('webpage').create();

page.open('http://blog.zenika.com/', function() {

  setTimeout(function() {
    page.render("/dev/stdout",{ format: "png" });
    phantom.exit()
  }, 1000);

});

System info

I tested this on 2 distinct systems and got the same result

Linux sebastien-xps 3.13.0-66-generic #108~precise1-Ubuntu SMP Thu Oct 8 10:07:36 UTC 2015 

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 12.04.5 LTS
Release:    12.04
Codename:   precise

Linux dev 3.13.0-65-generic #105-Ubuntu SMP Mon Sep 21 18:50:58 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.3 LTS
Release:    14.04
Codename:   trusty

Test 1

sudo apt-get install phantomjs

phantomjs -v -> returns 1.9.0

phantomjs recorder.js -> outputs binary data

Test 2

sudo npm install -g phantomjs@1.9.0-0

phantomjs -v -> returns 1.9.0

phantomjs recorder.js -> outputs nothing

---

@ariya I'll open an issue on the medium repository as it seems related to it only. I thought medium only handled the phantomjs-prebuild and that you managed the phantomjs package but it seems it's not the case and medium handles both.

[BlackCapCoder]

I am also suffering from this. This occurs with all writes to stdout, not just page.render. It is possible to "flush" the data out by writing more things to stdout/stdin.

const sys = require('system');
const inp = sys.stdin;
const out = sys.stdout;
const wp  = require('webpage');

var inst = new lorem ();

function lorem () {
  this.run = function (inp) {
    eval(inp);
  };

  this.ping = function () {
    out.writeLine("pong");
  }

  this.Open = function (url) {
    var page = wp.create();
    page.open("http://example.com", function(status) {
      out.writeLine("OK");
    });
  };
}

function listenIO () {
  setTimeout(function () {
    var ln = inp.readLine();
    inst.run(ln);
    // out.flush(); doesn't matter
    listenIO();
  }, 0);
}
listenIO();

$ phantomjs main.js
this.ping()
pong
this.ping()
pong
this.Open()
this.Open()
OK
this.Open()
OK
this.ping()
pong
OK
this.Open()
// lorem
OK
^C

[stale]

Due to our very limited maintenance capacity, we need to prioritize our development focus on other tasks. Therefore, this issue will be automatically closed (see #15395 for more details). In the future, if we see the need to attend to this issue again, then it will be reopened. Thank you for your contribution!