What's the future of OpenJDK?

Mark Wielaard mark at klomp.org
Tue Mar 2 14:08:56 UTC 2010

On Tue, 2010-03-02 at 14:26 +0100, Volker Simonis wrote:
> I can only agree with Mark Wielaard and his call to "Endorse and
> promote individuals, organizations and
> companies to contribute and encourage them to work together", although
> I think this will be a lot harder for the HotSpot VM case than for the
> J2SE libraries.

That is funny because I think it is the other way around actually.
Although technically challenging, in the end HotSpot is "just" a VM for
which there are pretty tightly defined constraints on how it should
work. We know how to replace it completely. See the Cacao integration in
IcedTea. And we have people hacking on significant projects like Zero
and Shark which replace huge chunks of it.

The core class libraries on the other hand are much more fuzzy, don't
have a very strict spec, and are mainly defined by current behavior of
the openjdk implementation. Changing anything here quickly runs into
either hard to judge "compatibility" discussions or politics over
how/when to extend the public api. Both of which are pretty much
impossible to test independently since the testsuite is basically "all
the programs ever written out there" which depend on all kinds of weird
quirks of the current implementation (we had to work pretty hard to be
bug compatible in GNU Classpath).

So from my perspective hacking on the VM is much easier since there are
already so many people out there who have hacked on various parts and
pieces that show that things will just work. While replacing parts of
the core class libraries has much higher risks of breaking stuff out



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