1302048 - Firefox hangs and crashes in [@ longcopy ]

Status: RESOLVED WORKSFORME

(Core :: JavaScript: GC, defect)

Description

[Laurentiu Pancescu]

This bug was filed from MDN. Firefox is hanging and manually crashing produces this crash report: https://crash-stats.mozilla.com/report/index/3f4647fd-4e36-47ed-8024-ad9a22160912

1. Clone https://github.com/lpancescu/xhr-memory-leak
2. Start a local web server in the clone directory (described in README.rst)
3. Open http://localhost:8000/leak.html
4. Wait a short while, while monitoring CPU and memory usage
5. After Firefox takes 100% CPU, try to close the tab

Firefox remains unresponsive, and it continues to leak memory indefinitely, without ever responding or closing the problematic tab. I used Firefox Developer Edition with a clean profile, immediately after "refreshing" Firefox.  I thought that a tab shouldn't be able to hang Firefox anymore, after the switch to multi-process (e10s)? Firefox 48.0.1, without e10s enabled, behaves exactly the same. During earlier tests, I had to kill the Firefox process from Activity monitor, to avoid OS X running out of memory.

Safari and Chrome also take 100% CPU after a while, but they remain responsive, and clicking the close button on the leak.html tab works immediately, without any issues.

Comment 1

[Abe - QA (:Abe_LV)]

Attachment: memory-report.json.gz

I have tested this by cloning the repo on XAMPP local server and it is reproducible.
Its memory usage increases and the browser will be unresponsive. In the first try, I had to close the browser by the task manager. In the second try, the browser crashed after certain time.  The memory report is attached. 

Here are some of the crashes: bp-4312013f-7686-4c33-8d14-8eeb62160916
                              bp-dcfc62a9-dd31-40b5-87a2-806fb2160916
                              bp-0c52d469-4c97-4fe8-b3d6-b55b52160916

Screen Capture: https://testing-1.tinytake.com/sf/OTc1MjkyXzQwNjY2ODE

--
Version 	50.0a2
Build ID 	20160916004005
Update Channel 	aurora
User Agent 	Mozilla/5.0 (Windows NT 10.0; WOW64; rv:50.0) Gecko/20100101 Firefox/50.0

Comment 2

[Laurentiu Pancescu]

I just tested again with Firefox 54.0.1 (release). The memory footprint increases and CPU usage reaches 100%, but it's now possible to simply close the tab - Firefox immediately responds to user input, just like the other browsers. I assume it was fixed by changes that occured in the last 11 months.  Marking as resolved. Thanks!