Subject: Re: PL/Java 1.5.1_BETA2
To: Christoph Berg <myon@debian.org>, pgsql-pkg-debian@postgresql.org,
 pgsql-pkg-yum@postgresql.org
References: <5B96B226.2080803@anastigmatix.net>
 <20180915203221.GA19015@msg.df7cb.de>
From: Chapman Flack <chap@anastigmatix.net>
Message-ID: <5B9D73A2.2090402@anastigmatix.net>
Date: Sat, 15 Sep 2018 17:03:30 -0400
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On 09/15/18 16:32, Christoph Berg wrote:
> Fatal Error: Unable to find package java.lang in classpath or bootclasspath
> ...
> openjdk-10-jdk is installed. Any idea what is missing?

With Java 9, a completely new modular structure was brought to the JDK,
with deep implications for build procedures. I will have to rework the
build process heavily for a future PL/Java release, but for 1.5.1, I
have not.

So, it needs a Java 8 JDK (or 7, or 6, but let's just say 8) to build.

Once built, it will _run_ on later Java runtimes (and users can write
PL/Java functions using the latest language features, compile them with
later JDKs, and run them in PL/Java, as long as it is running on a new-
enough runtime).

The Java runtime that actually gets used, at runtime, is determined by
the pljava.libjvm_location variable, which can be given a default at
build time with -Dpljava.libjvmdefault=....

So if you are packaging for a platform where you know Java 10 will be
the default, and you know what the conventional path to its libjvm.so will
be, then by all means, use -Dpljava.libjvmdefault= to build in that
default for use at runtime. But the build, for now, must be done with 8.

There is a new(-ish?) page in the documentation with information intended
for packagers:

http://tada.github.io/pljava/build/package.html

-Chap