Bug 13595 – Repeatedly accessing XHR.responseText on a large file (70MB) causes memory usage to balloon

• Component: XML
• Status: RESOLVED FIXED

[Antoine Quint]

Loading a large video file using XMLHttpRequest make the nightly WebKit application memory shoot up to about 800MB in 5 seconds, and keeps going up until no memory is left.

[Antoine Quint]

Created attachment 14359 [details]
Testcase

[Antoine Quint]

Comment on attachment 14359 [details]
Testcase

This testcase needs to be opened from the local filesystem given that it makes a call to another domain and would result in a JS exception if opened directly from the link within the bug.

[Alexey Proskuryakov]

It doesn't look like there's a leak here, but garbage collection doesn't free memory quickly enough.

[David Kilzer (:ddkilzer)]

<rdar://problem/5335880>

[Geoffrey Garen]

In particular, it looks like the problem is caused by this line
               var currentLength = xhr.responseText.length;
which causes the network data to be serialized to text every time a new chunk arrives.

Is there a real website that uses this technique?

[Alexey Proskuryakov]

Fixed by Maciej in r24633  (as <rdar://problem/5300291>).

[David Kilzer (:ddkilzer)]

(In reply to comment #6)
> Fixed by Maciej in r24633  (as <rdar://problem/5300291>).

Follow-up fix in r24637.