NativeJavaGcjPackages
Launchpad Entry: https://launchpad.net/distros/ubuntu/+spec/native-java-gcj
Created: 20051105 by MatthiasKlose
Contributors: MatthiasKlose
Interested: ZakElep
Packages affected: all packages containing java code (40 in main)
Summary
For each package containing java code, provide a corresponding -gcj package with java compiled to native code.
Rationale
Faster execution compared to the gij-interpreted java code. Tradeoff is higher memory consumption.
Design
Each jar file in a package installed into /usr/share/java has a corresponding file /usr/lib/gcj-4.0/ holding the corresponding so file containing the natively compiled java code. The jar file is built using the default java compiler using the arguments -O2 -fjni -findirect-dispatch.
gij is capable of working in both an interpreted mode and a compiled mode. In order to work with compiled packages, we will provide an extra package for each Java application and library that ends in -gcj which contains the compiled binaries.
To workaround limits on the number of class files and size of the byte-code, the compilation is done using the aot-compile-deb script.
The debugging symbols are provided in a corresponding -gcjdbg package.
Implementation
1. Update aot-compile-deb to compile the class/jar files in the temporary installation directories and install the results in the -gcj package(s).
2. Write a helper script for aot-compile-deb and gcj-dbtool calls. This helper script may be debhelper-based, cdbs based, or completely independant of both.
3. We will provide an example implementation for one package.
Steps to follow:
- add the two packages to the control file.
- call aot-compile-deb from the deb file.
- add gcj-dbtool calls to the postinst and preinst files.
- strip the symbols and put the symbols into the -gcjdbg package.
4. Coordinate community/developer support around updating all other Java packages (about 150 in main and universe, 40 just in main)