[SOLR-16500] Enable JDK 19 preview options for MMapDirectory V2

• Type: Task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: main (10.0), 9.2
• Component/s: scripts and tools
• Assignee: Kevin Risden
• Reporter: Christine Poerschke
• Created: 26/Oct/22 16:51
• Updated: 05/Apr/23 04:47
• Resolved: 28/Oct/22 16:23

Description

uschindler wrote on https://issues.apache.org/jira/browse/SOLR-16442?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17620361#comment-17620361 ticket:

We should also think of updating the startup scripts to pass --enable-preview to JVM if exactly Java 19 is detected. Elasticsearch and Opensearch will / have already done this. Not doing this will print a startup warning on Java 19 to Java logging.

The main reason to pass --enable-preview to the JVM is to allow MMapDirectory V2 to be enabled and memory mapping happening in larger junks for less overhead and use of kernel resources (see vm.max-map-count sysctl). It also reduces risk of crushing JDK on bad written plugins or bugs with reopening IndexSearcher/IndexReader.

See https://github.com/apache/lucene/pull/912 for more details.

Issue Links

• is superceded by: SOLR-16642 upgrade Solr to use Lucene 9.5.0
• relates to: SOLR-16442 Upgrade to Lucene 9.4.2 (do and document)
• links to: GitHub Pull Request #1142