Ubuntu Wiki

• Launchpad Entry: https://launchpad.net/distros/ubuntu/+spec/native-java-gcj

• Created: 20051105 by MatthiasKlose

• Contributors:

• Packages affected: all packages containing java code

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.
• 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.
• update aot-compile-deb to compile the class/jar files in the temporary installation directories and install the results in the -gcj package(s).
• The debugging symbols are provided in a corresponding gcjdbg package.

Implementation

• Provide an example implementation for one package:
  • add the two packages to the control file
  • call aot-compile-deb from the deb file (maybe add a debhelper to do that)
  • add gcj-dbtool calls to the postinst and preinst files (maybe add a debhelper to do that)
  • strip the symbols and put the symbols into the -gcjdbg package.
• Update all other java packages (about 150 in main and universe)