A Brief History of Just-In-Time


                              Urs Holzle
                  University of California, Santa Barbara


Java has popularized the concept of "just-in-time" compilation, i.e.,
compilation at runtime. Despite gaining this popularity only recently,
runtime compilation dates back more than two decades.  In this talk I
will give an overview of the history of runtime compilation, moving
from APL systems of the seventies to Smalltalk compilers of the
eighties to Java compilers of the nineties. 

I will conclude with a description of the "HotSpot" Java compiler that
is currently being developed at JavaSoft. HotSpot combines a fast
interpreter with a profile-driven optimizing compiler and a
high-performance runtime system, resulting in the fastest Java system
to date. In addition to a brief discussion of HotSpot's performance
relative to Microsoft's Java implementation, I will also speculate on
the evolution of Java performance over the next few years.