RE: [platform-core-dev] About the performance of jars and compression :

["Philippe Ombredanne" <pombredanne@xxxxxxxx>]

Proguard is one of the most commonly open source used there, AFAIK.
Typically a lot of the optimizations made by those tools:
- have been made void by modern optimizing JITs, and optimized JVMs
(i.e. inlining), but you may still win some by applying them statically,
bypassing VM warm-up times to discover hotspots, and perform JIT
optimization.
- are also detected through design time static analysis like the one
performed by the JDT, or Checkstyle &  PMD (i.e. detect unused imports,
fields, methods,.branches...).

IMHO, it would be hard to get it to work nicely with Eclipse's notion of
published vs. public APIs, and intensive dynamic class loading: the
amount of work to provide exceptions would be significant.
And like class ordering, because it might be costly and sensitive, it
may be worth only on some very specific sets of critical jars, like SWT,
or OSGI, where you may gain a few KB here and there, and a few secs.
My hunch is that a gentle optimization may be able to get ~5 to 10% size
reduction, based on past (non-eclipse) experience at most.

--
Cheers
Philippe

philippe ombredanne | nexB - Open by Design (tm)
1 650 799 0949 | pombredanne at nexb.com
http://www.nexb.com 
-----Original Message-----
From: platform-core-dev-admin@xxxxxxxxxxx
[mailto:platform-core-dev-admin@xxxxxxxxxxx] On Behalf Of Ed Burnette
Sent: Saturday, February 26, 2005 11:17 PM
To: platform-core-dev@xxxxxxxxxxx
Subject: RE: [platform-core-dev] About the performance of jars and
compression : some ideas for plugins installed as one jar.


Has anybody tried a java optimizer/obfuscator on Eclipse jars? Of course
it would have to be careful not to munge any public APIs but they can
potentially reduce jar sizes significantly. Here are some references:

http://proguard.sourceforge.net/alternatives.html
http://proguard.sourceforge.net/
http://preemptive.com/products/dasho/
http://jode.sourceforge.net/
http://www.sable.mcgill.ca/soot/
http://www.alphaworks.ibm.com/tech/JAX

 


From: platform-core-dev-admin@xxxxxxxxxxx
[mailto:platform-core-dev-admin@xxxxxxxxxxx] On Behalf Of Jeff McAffer
Sent: Saturday, February 26, 2005 10:54 PM
To: platform-core-dev@xxxxxxxxxxx
Subject: RE: [platform-core-dev] About the performance of jars and
compression : some ideas for plugins installed as one jar.



We did some experiements with class ordering in the jars.  It is
interesting but both costly and quite sensitive.  The classload order
depends on, of course, what you are doing.  What you are doing depends
on the state of the workspace you open.  This is free to change from run
to run.  The lower level plugins are roughly independent of the
workspace but they also only account for a small fraction of the classes
loaded in a typical session.   

Summary, something could be done here but the net benefit is
questionable since it can only be applied to a limited set of plugins
effectively. 

Jeff