[CentOS] OpenJDK vs Sun JDK

Fri Apr 16 07:36:09 UTC 2010
Christopher Chan <christopher.chan at bradbury.edu.hk>

On Friday, April 16, 2010 02:54 PM, Mathieu Baudier wrote:
>> RedHat has acknowleged that Sun's JDK is faster - despite the fact
>> OpenJDK is native. Since it's native, it also means it's not platform
>> independent (in the sense of compile once run anywhere.)
> What do you mean "is native" ?

I assumed he meant that the class files compiled by OpenJDK are native...

> The JDK (or rather the JVM) is native on all OS, since it is the layer
> which makes the Java compiled bytecode portable.
> OpenJDK could even be seen as more portable since the IcedTea build
> harness allows to port it to more platforms via the Zero JIT (there is
> a significant amount of processor-dependent assembler code in the JVM)
> I'm using OpenJDK on my servers and desktops under CentOS/Fedora for
> years, and my customers run the Java binaries on Windows without
> problem.

I guess that assumption can now go out the window. Maybe he was talking 
about gcj thinking it was OpenJDK...

I have no idea about speed difference, but I would be a bit surprised
> if it would be very big.
> My understanding is that the (native) Hotspot JVM is basically the
> same for both products and that the differences are about some java
> libraries.
> That would be interesting if you could send a reference to this Fedora thread.
> More generally OpenJDK is not a separate independent project (like
> Blackdown used to be, or Apache Harmony still is), this is just the
> Sun JVM codebase, with compatible licenses (some patches are then
> applied by the IcedTea build harness when building the binaries from
> OpenJDK sources).

Most of the Sun codebase anyway...