[Bug 78] Use pure Java implementation of zlib from Classpath instead of zlib for java.util.zip

[bugzilla-daemon at icedtea.classpath.org]

http://icedtea.classpath.org/bugzilla/show_bug.cgi?id=78





------- Comment #7 from adam at spicenitz.org  2007-11-08 04:00 -------
I've run some simple performance tests. "z.tar" was generated from the Linux
kernel source:
$ git archive --format=tar --verbose v2.6.23 > z.tar

$ java -version
java version "1.7.0"
IcedTea Runtime Environment (build 1.7.0-b21)
IcedTea 64-Bit Server VM (build 1.7.0-b21, mixed mode)


$ pv z.tar  | java TestDeflate gnu > z.tar.zz
using classpath.zip.DeflaterOutputStream
 252MB 0:01:02 [4.02MB/s]
[============================================================>] 100%            


$ pv z.tar  | java TestDeflate sun > z.tar.zz
using java.util.zip.DeflaterOutputStream
 252MB 0:00:53 [4.76MB/s]
[============================================================>] 100%            


$ pv z.tar.zz  | java TestInflate gnu > /dev/null
using classpath.zip.InflaterInputStream
54.7MB 0:00:04 [13.4MB/s]
[============================================================>] 100%            


$ pv z.tar.zz  | java TestInflate sun > /dev/null
using java.util.zip.InflaterInputStream
54.7MB 0:00:03 [15.2MB/s]
[============================================================>] 100%            



Not as good as native, but not too bad? Plus, these are short runs, so hotspot
presumably would improve performance a bit more over time. It's definitely a
performance hit, but is it bad enough to forget the idea? (How bad is selinux?
How about -D_FORTIFY_SOURCE=2?) And won't we all be a bit pleased when the next
zlib vulnerability is found.

It's probably not such a big deal, but I just spent the week reading the
libtiff source code, and I've become pretty skeptical of any compression code
written in C. So ignore me if I'm too crazy. :-)


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