[webkit-dev] Parallel image decoders are up for review

Alpha Lam hclam at chromium.org
Mon Jul 16 13:41:02 PDT 2012


This is great work!

There's work in the Chromium port going on that has a similar goal as your
parallel image decoding effort. There are some parts that we overlap that I
think should be discussed to avoid clashes.

Here's some background information of what we're doing. In Chromium port
there's a deferred painting mode that we record painting commands and
playback (rasterize) on another thread. Recording on the main thread
requires images to be synchronously decoded and our current focus is to
defer image decoding to a later time and eventually have parallel image

The specific part we overlap is drawing an asynchronously decoded
BitmapImage to GraphicsContext. Your patch does the whole image decoding
asynchronously while we just care about whether an image can be
asynchronously decoded or not. This part in particular I think we should
discuss to make sure we're both comfortable with.

I'll make a few comments on the patch in the webkit bug.

Thanks and this is great effort!


2012/7/9 KwangYul Seo <skyul at company100.net>

> Hi,
> Our team at Company 100 has worked on parallel image decoders for past a
> few weeks and some patches are pending for review now. Here is the master
> bug for parallel image decoders:
> https://bugs.webkit.org/show_bug.cgi?id=90375
> For the overall architecture and design, please refer to the following
> design document. We will update the design document as we change code after
> review.
> https://docs.google.com/document/pub?id=12gf7MhNHfupeR3GdRF-h2Vzg86viCbwXq8_JByHKlg0
> Our implementation shows considerable speedup in image intensive sites and
> no performance regression in PLT. Please refer to the master bug for
> specific numbers.
> We do understand many paralleization techniques make code so complex to
> the level that can't be accepted. So we tried our best to reduce the
> complexity of code, but reviewers can help us reduce it further.
> Regards,
> Kwang Yul Seo
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> webkit-dev mailing list
> webkit-dev at lists.webkit.org
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