1436225 - blocking script and cpu high with SetTimeout

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect, P3)

Description

[Karl Dubost💡 :karlcow]

This is a spin-off of https://webcompat.com/issues/5506

Navigate to: http://en.miui.com/forum.php?mod=viewthread&tid=556362&highlight=miui%2B9

Expected Behavior: It should load the full page.

Actual Behavior: It loaded the top portion of the page. Entire tab got frozen. CPU usage skyrocketed. A horizontal bar on top asked if i want to wait or stop the page.


This is happening from Firefox 55 to Firefox 60 (at least)
fwiw the same thing is happening in Chrome, but it handles it in a better way.
Chrome is giving this message

> stat.php?id=2441309&web_id=2441309:16 A parser-blocking, cross site (i.e. different eTLD+1) script, http://c.cnzz.com/core.php?web_id=2441309&t=z, is invoked via document.write. The network request for this script MAY be blocked by the browser in this or a future page load due to poor network connectivity. If blocked in this page load, it will be confirmed in a subsequent console message. See https://www.chromestatus.com/feature/5718547946799104 for more details.
na @ stat.php?id=2441309&web_id=2441309:16

also http://static.en.intl.miui.com/static/js/common.js?bX4z

```
Uncaught TypeError: Cannot read property 'addEventListener' of null
    at _attachEvent (common.js?bX4z:130)
    at header_extend.js?bX4z:16
```
which refers to

```js
function _attachEvent(obj, evt, func, eventobj) {
	eventobj = !eventobj ? obj : eventobj;
	if(obj.addEventListener) {
		obj.addEventListener(evt, func, false);
	} else if(eventobj.attachEvent) {
		obj.attachEvent('on' + evt, func);
	}
}
```

but indeed Chrome seems to handle it better.


when I force stop the script in Firefox.


```
Error: Script terminated by timeout at:
_relatedlinks/msg<@http://static.en.intl.miui.com/static/js/common_extra.js?bX4z:28:18
_relatedlinks@http://static.en.intl.miui.com/static/js/common_extra.js?bX4z:27:8
@http://static.en.intl.miui.com/static/js/common.js?bX4z line 521 > eval:1:1
run@http://static.en.intl.miui.com/static/js/common.js?bX4z:521:4
checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:528:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
checkrun/<@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:28
setTimeout handler*checkrun@http://static.en.intl.miui.com/static/js/common.js?bX4z:530:4
$F@http://static.en.intl.miui.com/static/js/common.js?bX4z:538:2
relatedlinks@http://static.en.intl.miui.com/static/js/common.js?bX4z:2199:2
@http://en.miui.com/forum.php?mod=viewthread&tid=556362&highlight=miui%2B9:3876:1
```

Comment 1

[Jason Orendorff [:jorendorff]]

This isn't the sort of thing we call a web compat issue. It's a quality of life issue. Unquestionably, we can do better.

Comment 2

[Firefox Bug Husbandry Bot]

Migrating Webcompat whiteboard priorities to project flags. See bug 1547409.

Comment 3

[Firefox Bug Husbandry Bot]

See bug 1547409. Migrating whiteboard priority tags to program flags.