Bug 136347 – WebContent hangs under SharedBuffer::duplicateDataBufferIfNecessary() while browsing some websites

• Component: WebCore Misc.
• Status: RESOLVED FIXED

[Pratik Solanki]

We've got reports of WebContent hangs when browsing some pages. The following two sites have been reported

<http://www.liverpoolway.co.uk/index.php?/forum/1-ff-football-forum/>
<https://sports.yahoo.com/blogs/mlb-big-league-stew/mo-ne-davis-has-rough-outing-in-tough-matchup-with-las-vegas-003922244.html>

The spins show us doing a lot of allocation and memcpy under SharedBuffer::createCFData()

16  WebCore::SharedBuffer::createCFData() + 50 (WebCore + 52722) [0x7fff8fd70df2] 1-16
  16  WebCore::SharedBuffer::data() const + 68 (WebCore + 53780) [0x7fff8fd71214] 1-16
    16  WebCore::SharedBuffer::buffer() const + 36 (WebCore + 53828) [0x7fff8fd71244] 1-16
      16  WebCore::SharedBuffer::duplicateDataBufferIfNecessary() const + 117 (WebCore + 13117829) [0x7fff909e6985] 1-16
        16  WTF::Vector<char, 0ul, WTF::CrashOnOverflow>::operator=(WTF::Vector<char, 0ul, WTF::CrashOnOverflow> const&) + 223 (WebCore + 13118159) [0x7fff909e6acf] 1-16
          16  _platform_memmove$VARIANT$Ivybridge + 49 (libsystem_platform.dylib + 4913) [0x7fff82e76331] 1-16

[Pratik Solanki]

<rdar://problem/18073745>

[Pratik Solanki]

Created attachment 237322 [details]
Patch

[Andreas Kling]

Comment on attachment 237322 [details]
Patch

r=me

[Andreas Kling]

Comment on attachment 237322 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=237322&action=review

> Source/WebCore/platform/SharedBuffer.cpp:359
> +    size_t newCapacity = std::max(static_cast<size_t>(m_size), currentCapacity * 2);

We could consider a less aggressive growth strategy here, e.g 1.25x instead of 2x.

[Pratik Solanki]

Committed r173080: <http://trac.webkit.org/changeset/173080>