Zlib level in JDK7

Steve Poole spoole at linux.vnet.ibm.com
Wed Feb 16 11:55:03 UTC 2011

On Tue, 2011-02-15 at 09:17 -0800, Xueming Shen wrote:
> 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

I can appreciate why you want to be cautious right now - but it is
important that the codebase is regularly upgraded. If IcedTea have shown
that 1.2.5 is "ok"  then I'd say the risk is quite low. 

For JDK 8 it would make sense to discuss the pros and cons of relying on
the system version of zlib.  I can make the case either way though.

> 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, 

So the risk is even lower then? :-)

> the
> only thing that might bring in some enhancement is "Faster Z_HUFFMAN_ONLY
> compression for images and other specialized compression", but given my 
> experience
> of measuring the improvement in the past, I doubt you actually benefit 
> from it in most of
> the use scenario.
I'm not sure this is about any particular improvement - its really just
about keeping current with someone else's codebase. 

> -Sherman
> 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 zlib that is so out of date.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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