SOLR-14335: Lock Solr's memory to prevent swapping

[janhoy]

See https://issues.apache.org/jira/browse/SOLR-14335
Goal of this PR is to start Solr with a custom bootstrap class, which delegates to Jetty's main. In the custom bootstrap class, we will then implement memroy locking through JNA

[janhoy]

I updated to have a separate bootstrap module, only generating a solr.jar witha single class in it. Also the MANIFEST now specifies main class and classpath, so you can run java -jar solr.jar --module=http and it will start Solr.

This is still gradle only, so ant server && bin/solr start will not work...

[dweiss]

This is a chance to clean up manual jar naming, actually. The classpath here should be something like this:
"Class-Path": configurations.runtimeClasspath.collect { "lib/${it.getName()}" }.join(' '))
then bootstrap would have accurate coordinates at the exact library versions it needs to launch. Plus -- the "rename" trickery wouldn't be needed anymore in server.gradle.

The name of the output artifact (bootstrap.jar) can be set in this project as well (so that it doesn't have a version in the name).
jar.archiveName = "boostrap.jar"

[janhoy]

I tried this, but got

• What went wrong:
  A problem occurred evaluating project ':solr:bootstrap'.

Not allowed to resolve configuration ':solr:bootstrap:runtimeClasspath' at configuration time (https://guides.gradle.org/performance/#don_t_resolve_dependencies_at_configuration_time). Please upgrade your plugins and double-check your gradle scripts (see stacktrace)

[janhoy]

If you get it working, you may in fact push a change to the PR branch

[janhoy]

Lucene and Solr development has moved to separate git repositories and this PR is being bulk-closed.\nPlease open a new PR against https://github.com/apache/solr or https://github.com/apache/lucene if your contribution is still relevant to the project.