The java version checker requires being written with java 7 APIs.
In order to use java 8 apis in other launcher utilities, this commit
moves the java version checker back to its own jar.
We no longer need animal sniffer because we use JDK functionality
(introduced in JDK 9) to target older versions of the JDK for
compilation. This functionality means that the JDK handles the problem
of ensuring that we do not use JDK APIs from the version that we are
compiling from that are not available in the version that we are
compiling to. A previous commit removed this for the REST client (where
we target JDK 7) but a few traces were left behind.
This commit reorganizes some of the content in the configuring
Elasticsearch section of the docs. The changes are:
- move JVM options out of system configuration into configuring
Elasticsearch
- move JVM options to its own page of the docs
- move configuring the heap to important Elasticsearch settings
- move configuring the heap to its own page of the docs
- move all important settings to individual pages in the docs
- remove bootstrap.memory_lock from important settings, this is covered
in the swap section of system configuration
Relates #27755
JDK 9 has removed JVM options that were valid in JDK 8 (e.g., GC logging
flags) and replaced them with new flags that are not available in JDK
8. This means that a single JVM options file can no longer apply to JDK
8 and JDK 9, complicating development, complicating our packaging story,
and complicating operations. This commit extends the JVM options syntax
to specify the range of versions the option applies to. If the running
JVM matches the range of versions, the flag will be used to start the
JVM otherwise the flag will be ignored.
We implement this parser in Java for simplicity, and with this we start
our first step towards a Java launcher.
Relates #27675
Ryan Ernst
Jason Tedor