https://bugs.openjdk.org/browse/JDK-8337681
-phil.
On 8/1/2024 10:08, Daniel Gredler wrote:
Thanks for the confirmation!
I went ahead and made some measurements, and the improvement
possibilities really are quite good -- in a local test
PNGImageWriter.write( ) and callees were initially showing up as an
allocation hotspot (~400k objects / ~65 MB allocated), but after some
optimizations I'm seeing much better numbers (~400 objects / ~740 KB
allocated).
I also spent some time creating regression tests for different
combinations of alpha pre-multiplied vs. not, BufferedImage vs. other
image types, untiled vs. single-tile vs. multi-tile, custom source
bands vs. none, etc.
I've filed a bug (internal review ID 9077379), but do not have a bug
number yet. Once I have a bug number I'll submit a PR for review.
Take care,
Daniel
On Wed, Jul 31, 2024 at 8:13 PM Philip Race <[email protected]>
wrote:
I think yes.
Whereas JPG grabs the raster for the whole image whereas as you
noted,
PNG is looping row by row,
so there might need to be some updates in the handling of the child
raster needed.
-phil.
On 7/31/24 10:02 AM, Daniel Gredler wrote:
> Hi all,
>
> I'd like a quick sanity check on a possible memory inefficiency in
> PNGImageWriter.
>
> Some of the other image writers, like JPEGImageWriter, do their
best
> to avoid duplicating the image raster + data buffer [1]...
although it
> doesn't look like this was always the case [2].
>
> The PNGImageWriter, on the other hand, always makes a new raster +
> data buffer copy for each row [3]. It *is* per-row, so the data
isn't
> all duplicated in one go, but even on a row-by-row basis, it
ends up
> being quite a bit of unnecessary allocation and subsequent garbage
> collection.
>
> Can somebody confirm if I'm reading things right, and whether
> PNGImageWriter would benefit from a similar BufferedImage + single
> tile check, such as already exists in JPEGImageWriter?
>
> Thanks!
>
> Daniel
>
> [1]
>
https://github.com/openjdk/jdk/blob/e4c7850c177899a5da6f5050cb0647a6e1a75d31/src/java.desktop/share/classes/com/sun/imageio/plugins/jpeg/JPEGImageWriter.java#L415
> [2] https://bugs.openjdk.org/browse/JDK-6266748
> [3]
>
https://github.com/openjdk/jdk/blob/e4c7850c177899a5da6f5050cb0647a6e1a75d31/src/java.desktop/share/classes/com/sun/imageio/plugins/png/PNGImageWriter.java#L923
>
