Inflater/Deflater improvements

Clemens Eisserer linuxhippy at
Mon May 18 19:03:02 UTC 2009

Hi Ulf,

I don't think the JVM uses the Inflater/Deflater classes directly, but
instead accesses zblib directly - but I could be wrong.
Furthermore as far as I know charsets.jar isn't compressed.

The patches only try to remove some horrible memcpy overhead in some
common situation.

- Clemens

2009/5/18 Ulf Zibis <Ulf.Zibis at>:
> Am 04.05.2009 23:38, Martin Buchholz schrieb:
>> I think many people will be interested in performance improvements
>> in Inflater/Deflater.  I may have time to help review.
> Yes, there is also interest from charset de/encoding side. See:
> Current charset mapping tables are hosted as huge String constants inside
> charset classes. Hosting them as resource data files would would avoid ~50 %
> disk-footprint wastage of the charsets.jar. Additionally sharing of
> overlapping charset mapping data would become manageable. Currently we only
> have ClassLoader#getResouceAsStream() to load such data files, but we can't
> use it, because the underlying buffered stream is too slow in respect of JVM
> startup time. We need fast nio direct buffer access via
> java.nio.channels.Channel to load the data from charsets.jar.
> So improving performance of jar/zip file access would be much appreciated.
> :-)
> -Ulf

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