RE: Java and CPU

["Larry Loen" <lwloen@xxxxxxxxxx>]

Joe wrote:

>Java isn't eRPG, Brad.  It's an interpreted language.

This is a surprising statement.

Practically no one has been running interpreted Java for the last
three years, minimum.  At least, not on a server.  And, not for long
on the client.

Everyone has been doing Just In Time compiling or, on the '400,
direct (compiled) execution.  JITs may interpret for a while during
startup, but that all the interpretation anyone does nowadays.

Interpreted Java has become a Unicorn, and always was on iSeries.

I'm surprised how many people still think Java is largely an
interpreted language.  Interpretation is nowadays restricted to very
specialized situations like embedded.  And, pretty universally,
not on our box.

Servlets can beat CGI in several circumstances, because it
is basically firing up a waiting native thread instead of the potential
for creating a new job, creating a new activation, etc. that can
be part and parcel of running CGI.

And, throw enough SQL DB in the mix or enough back-end RPG
processing on the other end of a data queue or something,
and you won't be able to tell which approach is faster,
because the back end work will drown out the rest.

Someone had a nice COMMON presentation explaining all
this.

Now, I'm not going to argue whether Java is faster, on average,
than RPG.  I will tell you that when RPG is faster, it is not because
the codegen quality is better for RPG; it has to do with how RPG invokes
OS/400 services to advantage, which it was built to do (whereas
Java uses only very generic interfaces).



Larry W. Loen  -   Senior Java and AS/400 Performance Analyst
                          Dept HP4, Rochester MN


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