For those trying Java 21 with Solr, if you find the performance to be bad then try setting -Dorg.apache.lucene.store.MMapDirectory.enableMemorySegments=false This made a huge difference for me on our Solr nodes at work.
I filed the following ticket to Solr that ought to avoid the JDK performance regression if done: https://issues.apache.org/jira/browse/SOLR-17375 ~ David Smiley Apache Lucene/Solr Search Developer http://www.linkedin.com/in/davidwsmiley
