zlib configuration : system vs. bundled

[Baesken, Matthias]

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 ?

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 .


At least I think  building.md  should be fixed to  state the real status , the current  info is wrong :


"Certain third-party libraries used by the JDK (libjpeg, giflib, libpng, lcms
and zlib) are included in the JDK repository. The default behavior of the
JDK build is to use this version of these libraries, but they might be
replaced by an external version. To do so, specify `system` as the `<source>`
option in these arguments. (The default is `bundled`)."



Btw  how is building.html  generated ,  is this coming from  building.md  ?

Best regards, Matthias




> -----Original Message-----
> From: Alan Bateman <Alan.Bateman at oracle.com>
> Sent: Dienstag, 14. Mai 2019 17:47
> To: Baesken, Matthias <matthias.baesken at sap.com>; 'build-
> dev at openjdk.java.net' <build-dev at openjdk.java.net>
> Subject: Re: zlib configuration : system vs. bundled
> 
> On 14/05/2019 15:58, Baesken, Matthias wrote:
> > :
> >
> > On the other OS platforms, in case a zlib is found on the system :
> >
> >    if test "x${ZLIB_FOUND}" != "xyes"; then
> >      # If we don't find any system...set default to bundled
> >      DEFAULT_ZLIB=bundled
> >    fi
> >
> > we use it from the system .
> > Wouldn't  it be more  consistent to  have  zlib=bundled as well as default for
> the other UNIX platforms + MacOSX ?
> > ( people who wish to use  the system zlib still can configure it )
> >
> > Otherwise we often run into using old zlib installations at build time which
> might not be desired.
> >
> It was a deliberate change in JDK 9 to use the system zlib if possible.
> Windows is the outlier. If you through the archives of core-libs-dev
> then you should find several discussions about this, I think the most
> recent was in 2016, subject line "JDK-8031767 Support system or
> alternative implementations of zlib".
> 
> -Alan