Performance issue: jar vs. bin/classes

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77Scorpio - 17 Apr 2006 09:56 GMT

I was wondering whether there is a performance difference between java
appications packed into jar files and java applications which are
spread as .class files

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Brzezi - 17 Apr 2006 12:48 GMT

pon, 17 kwi 2006 o 10:56 GMT, 77Scorpio napisał(a):

> I was wondering whether there is a performance difference between java
> appications packed into jar files and java applications which are
> spread as .class files

what do u mean by "performance"?

starting program of course will be a little bit slower, coz jar it`s zip,
but files can be storede without compression, IMHO you can pass over this
problem

during runnig of program, there is no difference...

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Martin Gregorie - 17 Apr 2006 12:49 GMT

> I was wondering whether there is a performance difference between java
> appications packed into jar files and java applications which are
> spread as .class files

Compressed or uncompressed JAR files?

JAR files will reduce i/o overheads (only one file to open, less to read
if compressed).

A compressed JAR file will add to CPU loading (cycles used to decompress
classes)

Whether using a JAR file increases performance or not depends on both
i/o performance and CPU speed. If the application loaded over the 'net
(i.e. is an applet) then using a JAR file is usually recommended.

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Brzezi - 17 Apr 2006 13:17 GMT

pon, 17 kwi 2006 o 13:49 GMT, Martin Gregorie napisał(a):

> JAR files will reduce i/o overheads (only one file to open, less to read
> if compressed).

but even loading not compressed jar makes overheads, because loader must
interpret jar(zip) file, but that overheads are so small, so it can be omitted

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Martin Gregorie - 17 Apr 2006 18:47 GMT

> pon, 17 kwi 2006 o 13:49 GMT, Martin Gregorie napisał(a):
>
[quoted text clipped - 3 lines]
> but even loading not compressed jar makes overheads, because loader must
> interpret jar(zip) file, but that overheads are so small, so it can be omitted

Depends on your hardware and software. Both must be considered:

- If your CPU is fast but you're using an OS with slow i/o
(e.g. Windows 9x) the JAR file most likely be faster.

- If your CPU is slow (<300 MHz) but your OS has fast, multi-threaded
i/o (e.g Linux) the chances are that using a JAR file is slower.

- If you're reading the classes over a comms line then the JAR file
will almost always be faster.

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Roedy Green - 17 Apr 2006 19:42 GMT

>I was wondering whether there is a performance difference between java
>appications packed into jar files and java applications which are
>spread as .class files

jars are more compact for transmission. Class files don't need to be
decompressed.

Usually the jars are the way to go. Class files are just too messy and
hard to control. With a jar you know exactly what classes are being
used.

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Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

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Performance issue: jar vs. bin/classes

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