Hi,
today I’ve run the same benchmarks as last week (last WMS shootout) to see how
the new PNG encoder performs under OpenJDK 7 (1.7.0_45), which is known to
have a slower rasterizer but better scalability.
Well… have a look, this is the comparison between JDK own PNG encoder, ImageIO
native one, and the new pure java PNGJ based encoder (community module):
See anything? No? Well, let me try to show the comparison between last week JDK 7 results and this
week OpenJDK 7 on just the PNGJ based encoder:
Got the message now? 
Full details here:
https://docs.google.com/spreadsheet/ccc?key=0Aq3GF1EnUyHEdHVodEpjNHM0MVhEMlhPcmJHTTFCTWc&usp=drive_web#gid=2
Long story short, at 1 thread OpenJDK 7 is slower, but it matches Oracle JDK already at 2 and
gets better quickly as we go up with the number of threads*.
And while even the ImageIO native encoder gets a benefit from using OpenJDK 7 (10-15% faster than
with Oracle JDK), the PNGJ based encoder really shines with it… while my previous mail was really
good news for Windows 64 bit users, I’m picturing very large smiles on Linux user faces today** 
Cheers
Andrea
*: This does not mean OpenJDK will be better for any kind of map, the denser the map, the slower
OpenJDK 7, since it’s really slower at rasterizing. The maps in the last WMS shootout were not really
that dense (the typical OSM map has more elements in it)
**: OpenJDK binary builds are not officially available for Windows, however, for those that dare
to try, there are unofficial builds here:
https://github.com/alexkasko/openjdk-unofficial-builds
Would be nice to hear from Windows users how these perform (and how stable they are)
–
==
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