RFR(M): 8249963: Make the zlib implementation selectively configurable at startup

[Alan Bateman]

On 24/07/2020 12:48, Volker Simonis wrote:
> :
>
> I can't see much complexity here. If you look at the change you'll see
> that it's rather trivial. All it does is substituting some direct
> calls into the zlib library by indirect calls through
> function pointers.
>
I don't think the JDK should be in the business of loading several 
versions of zlib at the same time and using some functions from one 
version, and some functions from another. Have you explored solutions 
that don't burden the JDK? Has there been any attempt to bring the 
performance improvements from the different sources into one build as 
that seems to be what you are really looking for.

I would expect most/all of the Linux distributions to configure 
--with-zlib=system as they don't want a zlib in the JDK run-time image. 
So it might be unusual to build with --with-zlib=bundled and then expect 
to be able to use an alternative zlib. There was a good discussion on 
this topic on build-dev in 2016 as there was interest from Intel 
engineers at the time to be able to use their accelerated library.

Separately, I think it would be useful to explore some of the examples 
to see if they make use of the Vector API or if there are opportunities 
to do pure Java implementations that would benefit from the runtime 
compilers.

-Alan