Which Java JRE?

Arigead captain.deadly at gmail.com
Wed Dec 2 13:12:55 CET 2009

Bernd Pru"nster wrote:
> Martin Jansa wrote:
>> On Thu, Nov 26, 2009 at 03:06:35PM +0000, Arigead wrote:
>>> Hello all,
>>>     I'm working on a project and I think it'd be cool as to show off the
>>> project's work on a phone. The OpenMoko phone ;-)
>>> Unfortunately the project is implemented in Java, which I'm no fan of on
>>> anything but a web server or browser but that's a discussion for another
>>> day.
>>> I tried our system, which is running in an OSGi Container, on Jamvm on
>>> the OpenMoko. It works but it sucks up 95% of the CPU when it's idle.
>>> Not Good! I tried the same on my eeePC and with Sun's JRE our system
>>> uses 1% of CPU whilst JamVM on the eeePC uses 40%. Obviously JamVM does
>>> not suit our system.
>> No idea if it would be better, but have you tried cacao? Its in shr-feeds now again.
> This is really weird!
> I wrtoe one more or less serious app in java for the freerunner and a 
> couple of test apps and jamvm had avery fast startup, but was not as 
> compatible as cacao, but easier to use and did not require that much 
> ressources.
> which distro are you using? which feed are you using to install jamvm 
> (dunno if still true but there used to be a difference depending on 
> where you installed it from).

Sorry I've been a bit busy on stuff and only now catching up here on the

I'm using the latest classpath 0.98 and Jamvm 1.5.3  I can't remember
the specifics at the moment but there was some feature of Java 6 that
our system's code was using which required JamVM 1.5.3 which in turn
required Classpath 0.98. I just used a OE recipe for those and build
them for the OpenMoko.

I tried the Cacao JRE on my eeePC and it soaked up resources as well so
I never even bothered to build it for the phone. Obviously something in
our Java System, mabe knophlerfish is not streamlined in these JRE's.
There is a Huge difference in running our system in a SUN JRE (1% CPU
According top) and other Jre's

I'm working now on the eeePC to see can I reduce this 40% on Jamvm. When
I get time actually I'm now trying to connect to an AdHoc wifi network
form the FreeRunner.

Thanks for the clarification on the ARM front. I don't think Sun have a
JRE for an ARM 4, no surprise really ;-) Things would be too easy.

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