zlib configuration : system vs. bundled

[Baesken, Matthias]

Hello Alan, 

I found 

http://mail.openjdk.java.net/pipermail/core-libs-dev/2015-March/032106.html

and

http://mail.openjdk.java.net/pipermail/build-dev/2016-February/thread.html#16602

but without much details  on   real  or potential  performance improvements .

Both discussion  threads are pretty old.  I do not think they cover  the  changes  done in the meantime in   jdk9 and higher    in the java.util.zip package .
I think a lot of coding there moved  from C  to  Java ,  so  the libz   is used in JDK  less these days than  in  the "old times " .

>
> Sure but the opposite can arise too, say where someone is using a JDK
> release that bundles an older version of zlib.
>

True ,  unfortunately  the  old JDK  with bundled  libz   would  not use the  "great new  current   libz"  from the distro (in case there is such a recent version available ),
People would need to patch the JDK .

At least we have the freedom to  choose with the configure-flags .

Best regards, Matthias 


> On 15/05/2019 09:16, Baesken, Matthias wrote:
> > Hi Alan,   thanks for pointing me  at the old discussion .
> >
> > http://mail.openjdk.java.net/pipermail/build-dev/2016-
> February/016602.html
> >
> > talks about performance benefits .  Are you aware of some  benchmarks
> that showed the improvements ?
> If you can find the mails that references the Intel IPP library then you
> might have links to performance data comparing the different
> implementations. There is also mails somewhere in the archive with a
> proposal or patch to have the JDK select an alternative implementation
> at run-time, equivalent to LD_PRELOAD. I think we ended up with the
> right default.
> 
> >
> > In reality,  if you have the latest  distro versions you might be lucky and you
> have a nice recent zlib 1.2.11  .
> > However on older distros , you run in reality  into older zlibs  (often I see
> 1.2.8).  I don't think that this is a very good status .
> Sure but the opposite can arise too, say where someone is using a JDK
> release that bundles an older version of zlib.
> 
> I agree with the comment that the building instructions need to be
> sync'ed up.
> 
> -Alan.