Re: Java Batch

On May 3, 5:32=A0am, Pakku <pa...@[EMAIL PROTECTED]
> wrote:
> I've spent much of this morning looking for some comparison between
> the performance of Java and COBOL for batch programming on z/OS. =A0I
> haven't found any useful information and am hoping I might find some
> here.
>
> I know that IBM bought the JZOS product a couple years back with the
> intent of enabling Java in the batch world.
> Has this taken off?
>
> Also read somewhere that given that Java has to be reinterpreted (from
> the bytecode produced by compilation) by the JVM at runtime,

Most Java uses JIT (Just In Time) compiles that turn the byte code
into machine code once for each run unit, so batch processing will
only have a small overhead for the first transaction. Some Java do go
directly to machine code, such as GNU's Java gjc. It could even (but I
don't know if it does) save the machine code objects output from the
JIT and reuse these on the next run unless the byte code file has
changed (this is what Python does).

> there is
> no way it could outperform COBOL in classical batch processes like
> payroll or month-end credit card statement processing.

It is likely that much of the time the program is waiting for file
transfers, database results or similar. If the Java does the same
accesses then it will run in a similar time.


> Is this so?
>
> Would really appreciate hearing from anyone who has experience with
> JZOS or other forms of running batch Java on MVS.
>
> Thanks!