Reviewed by Darin.
<rdar://problem/5355951>
plainText() fragments TCMalloc heap badly on large pages
also likely fixes some cases of
<rdar://problem/5335382>
CrashTracer: [REGRESSION] 73 crashes in Safari at com.apple.WebCore: WebCore::DeprecatedStringData::increaseUnicodeSize + 52
If you load http://dscoder.com/test.txt with WebKit build with TCMalloc and system malloc you see that
Safari RPRVT with TCMalloc is 118.8MB
Safari RPRVT with system malloc is 69.7MB
Difference is almost entirely caused by heap fragmentation from a full document plainText() call (for indexing purposes).
The patch helps in two ways:
- construct plainText string in pieces to avoid O(n^2) reallocs
- allocate buffers using system malloc so they can be returned back to OS and don't fragment and grow TCMalloc heap
This shrinks http://dscoder.com/test.txt RPRVT to 79.0MB and makes full document plainText() take 50ms instead of 500ms.
The benefits are not limited to extreme cases, web pages above ~200kB can show substantial improvement in RPRVT.
* editing/TextIterator.cpp:
(WebCore::plainTextToMallocAllocatedBuffer):
(WebCore::plainText):
* editing/TextIterator.h:
* page/mac/WebCoreFrameBridge.mm:
(-[WebCoreFrameBridge selectedString]):
(-[WebCoreFrameBridge stringForRange:]):
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@24832 268f45cc-cd09-0410-ab3c-d52691b4dbfc
4 files changed
