It would seem that recent versions of Lucene, and in particular the one included in the currently WildFly, rely on jdk.management to tune their memory consumption estimates. Not doing so leads to those estimates being off and a warning being logged on first use of the relevant classes.

For some reason the warning does not appear in test logs of the WildFly test suite, but it does appear in the server.log created by tests, e.g. running HibernateSearchLuceneSimpleTestCase will cause the warning to appear in testsuite/integration/basic/target/wildfly/standalone/log/server.log.

I do not think this leads to critical problems, probably just unoptimized frequency of flushes to disk, but that's probably something we should improve on anyway.

See https://hibernate.zulipchat.com/#narrow/stream/132092-hibernate-search-dev/topic/Lucene.20warning , org.apache.lucene.util.RamUsageEstimator,  org.apache.lucene.util.HotspotVMOptions