IBM has setup a special group concerned with improving the performance of Java. Robert F. Berry of IBM tells us of their efforts.
JVM innovation is manly driven by performance enhancements. It started out on the client side, but today Java is relay big on the server side.
Java performance on a specific hardware has developed into a major selling point.
Performance Improvements
In the memory management area, an enhanced fully threaded Marc/Sweep/Compact algorithm was developed which uses system idle time for marking and does incremental compaction.
IBMs Just in time Compiler (JIT) uses an aggressive in-lining technique which gives the jit much more code to look at and optimize. Object allocations can be improved by static analysis of their locality and then probably allocate them on the stack and thus also save on synchronization time.
Restarting a JVM is expensive, but from a transaction isolation point this is a useful concept. To make this a viable solution a JVM start and clean mechanism has been developed where several JVMs are sharing part of their environment. The startup time for an additional JVM has been reduced by about a magnitude.
Future Work
Footprint Size
Very Large Heaps gt 500 GB
Very Large Systems (n-Way Servers)
Object Pooling (e.g Jakarta Commons)
Improve decimal arithmetics for banking transactions
Improve performance on XML and XST workloads for Webservices
Conclusion
I find it rather hard to write a report on a topic I am not really fluent in :)