Zlib level in JDK7

Xueming Shen xueming.shen at oracle.com
Tue Feb 15 17:17:57 UTC 2011

  One of the benefits of using a 5-year old version is that it has been 
thoroughly tested by
various software for 5 years, given we actually don't have lots of tests 
for zlib ourself, this
is very important, at least for me, when considering upgrade, especially 
at this late stage
of the release I would be very cautious to do it. While the changelog 
lists a "long" list of
changes from 1.2.3. to 1.2.4, most of them are in code that are not 
included in JDK, the
only thing that might bring in some enhancement is "Faster Z_HUFFMAN_ONLY
compression for images and other specialized compression", but given my 
of measuring the improvement in the past, I doubt you actually benefit 
from it in most of
the use scenario.


On 2/15/2011 5:57 AM, Alan Bateman wrote:
> Steve Poole wrote:
>> Hi all,
>> JDK7 is using zlib 1.2.3 (which was added to JDK7 back in 2009.)
>> Zlib's latest version is 1.2.5 - is there any expectation to move to
>> 1.2.5 in JDK7?   It seems a real shame to ship JDK7 with a version of
>> zlib that is so out of date.
>> More than happy to help contribute towards making this happen.  I would
>> like to know if its already on someone's radar though  or to understand
>> why this is a mad idea :-)
>> Cheers
>> Steve
> I don't think it's on anyone's radar. Sherman did the last update, 
> bringing us up from a patched 1.1.3 to 1.2.3. The main thing with zlib 
> updates is testing and bake time. Have you done any testing with 
> 1.2.5? While there are some good reasons listed in the ChangeLog, I'm 
> curious if they translate into any measurable improvement with the zip 
> APIs. On the testing it would be interesting to check if 1.2.5 is used 
> by any of the distros as I think (but might be wrong) that 
> OpenJDK/IcedTea6 project have changes to use /usr/lib/libzip.so rather 
> than the snapshot in the jdk repository and so might already have 
> experience using the latest version.
> -Alan

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