Miscellaneous improvements to "jar".

[Xueming Shen]

Martin Buchholz wrote:
>
>
> On Fri, Jun 26, 2009 at 01:37, Ulf Zibis <Ulf.Zibis at gmx.de 
> <mailto:Ulf.Zibis at gmx.de>> wrote:
>
>     Am 26.06.2009 02:57, Martin Buchholz schrieb:
>
>         I did some benchmarking,
>         and found that my changes "only" make jar 10-20% faster.
>         Disappointing - we expect an order of magnitude for every commit!
>
>
>     1. Hopefully some volunteer would be found to fix
>     http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6818737
>     before JDK7 API-freeze.
>     Especially, if jar is not compressed, as in case of normal JDK
>     installation, reading entries from jar should be much faster
>     through java.nio.channels, than via BuffererdInputStream.
>
>
> The way to motivate us around here
> is to provide the prototype implementation that
> demonstrates the speedup.
Ulf,

I do have a "prototype implementation" that uses buffer based read/write 
on Jar/ZipFile, it
is not that "much" faster as you would have expected (basically the gain 
of using direct buffer
comes from saving one or two memory copy of the content,  which is very 
faster, compared to
the "real hard" work of moving bits from harddisk to memory). While it's 
still something
worth doing,  but definitely not a high priority for now, yes, it's on 
the list.

Sherman