Bug 20054

Summary: Showing large plain-text files is extremely slow
Product: WebKit Reporter: Benjamin Meyer <ben>
Component: Layout and RenderingAssignee: QtWebKit Unassigned <webkit-qt-unassigned>
Status: RESOLVED DUPLICATE    
Severity: Major CC: eike.ziller, jturcotte, kenneth, kling, laszlo.gombos
Priority: P1 Keywords: Performance, Qt
Version: 528+ (Nightly build)   
Hardware: PC   
OS: All   
Bug Depends on:    
Bug Blocks: 35784    
Attachments:
Description Flags
Large text file none

Benjamin Meyer
Reported 2008-07-16 07:45:13 PDT
What steps will reproduce the problem? 1. dd if=/dev/urandom of=/tmp/test.txt bs=1024 count=256 2. go to uri file:///tmp/test.txt What is the expected output? What do you see instead? Mozilla shows this file in about 1 second. QtWebKit from Qt 4.4 Please provide any additional information below. Showing this file takes about 60 seconds on my machine. I tracked down the issue to the fact that in bidi.cpp we are calling nextBreakablePosition over and over which constructs a QTextBoundryFinder
Attachments
Large text file (345.83 KB, text/plain)
2009-12-02 02:13 PST, Jocelyn Turcotte 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Benjamin Meyer
Comment 1 2008-07-16 07:50:06 PDT
I started hacking around and made a branch that passes all of the tests and re-uses the iterator when possible, but it is a bit of a hack and when you enable the other iterator caches there are three failures which doesn't make any sense... And it can still crash an iterator is created, the string is deleted a new string is created at the same location in memory, but with a different lenght and a new iterator is created with it. We should just see about re-using the same iterator upstream. Branch: http://code.staikos.net/cgi-bin/gitweb.cgi?p=webkit;a=shortlog;h=bmeyer/fasttext Diff: http://code.staikos.net/cgi-bin/gitweb.cgi?p=webkit;a=blobdiff;f=WebCore/platform/qt/TextBreakIteratorQt.cpp;h=94aafdba5e8fd2e261caa4b446756112e1a3c2c6;hp=88b96808650ed290ea328208157d2f965089d39e;hb=95c45c80fc64841cfc262facaba34750b9ca5138;hpb=af6eca2c5a5ec7e5a462ad211f8f1e3cb9bdef86
Benjamin Meyer
Comment 2 2008-07-16 09:22:37 PDT
Probably worth looking into what the average length is. Maybe we could get rid of the buffer
Kenneth Rohde Christiansen
Comment 3 2009-10-04 07:31:33 PDT
There have recently been some commits that could improve this: https://bugs.webkit.org/show_bug.cgi?id=29092 Can you tell me if this is still an issue?
Jocelyn Turcotte
Comment 4 2009-12-02 02:13:46 PST
Created attachment 44137 [details] Large text file Example generated using: dd if=/dev/random bs=1024 count=256 | base64 > large.txt The bug is still present, reloading this file locks the browser for 20 seconds, it loads instantly in firefox.
Jocelyn Turcotte
Comment 5 2010-03-03 06:12:00 PST
This bug has to be fixed for QtWebKit 2.0
Andreas Kling
Comment 6 2010-03-10 10:03:52 PST
*** This bug has been marked as a duplicate of bug 31719 ***
Benjamin Meyer
Comment 7 2010-03-10 11:52:35 PST
Shouldn't that one be a duplicate of this issue as this is the older issue?
Andreas Kling
Comment 8 2010-03-10 17:21:12 PST
I opted for keeping the other one since it had more useful information.
Note You need to log in before you can comment on or make changes to this bug.