Nigel Horspool          
U. Victoria, Canada
nigelh@csr.uvic.ca

Implementing Java Exceptions Efficiently


Throwing and catching an exception in Java is remarkably expensive.
Implementers have apparently taken the view that exceptions are
rare events and that efficiency is unimportant.  We take the view
that exceptions should be a standard programming pattern and that
efficiency does matter.
We first examine where all the time is taken.  Then, based on these
experimental observations, we recommend strategies for making
significant reductions in execution time.  Our recommendations do
not require any changes in the class file format. 
We further propose modest changes to the Java language and to the
class library that would ease the burden on the implementer of
the exception handling mechanism.


Acknowledgement: Mike Zastre has contributed to this work.