Sometimes (especially when under higher load), Artemis throws the following exception:

[10:03:01.377] ERROR [Thread-9 (ActiveMQ-IO-server-org.apache.activemq.artemis.core.server.impl.ActiveMQServerImpl$6@2484c868)] o.a.a.a.journal - AMQ144003: Error compacting java.lang.reflect.InvocationTargetException: null at java.base/jdk.internal.reflect.GeneratedMethodAccessor991.invoke(Unknown Source) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at io.netty.util.internal.CleanerJava9.freeDirectBuffer(CleanerJava9.java:88) at io.netty.util.internal.PlatformDependent.freeDirectBuffer(PlatformDependent.java:392) at org.apache.activemq.artemis.core.io.mapped.MappedSequentialFileFactory.releaseBuffer(MappedSequentialFileFactory.java:134) at org.apache.activemq.artemis.core.io.mapped.MappedSequentialFile.writeDirect(MappedSequentialFile.java:272) at org.apache.activemq.artemis.core.io.mapped.TimedSequentialFile.writeDirect(TimedSequentialFile.java:164) at org.apache.activemq.artemis.core.journal.impl.AbstractJournalUpdateTask.flush(AbstractJournalUpdateTask.java:217) at org.apache.activemq.artemis.core.journal.impl.JournalImpl.compact(JournalImpl.java:1613) at org.apache.activemq.artemis.core.journal.impl.JournalImpl$14.run(JournalImpl.java:2159) at org.apache.activemq.artemis.utils.actors.OrderedExecutor.doTask(OrderedExecutor.java:42) at org.apache.activemq.artemis.utils.actors.OrderedExecutor.doTask(OrderedExecutor.java:31) at org.apache.activemq.artemis.utils.actors.ProcessorBase.executePendingTasks(ProcessorBase.java:66) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) at org.apache.activemq.artemis.utils.ActiveMQThreadFactory$1.run(ActiveMQThreadFactory.java:118) Caused by: java.lang.IllegalArgumentException: duplicate or slice at jdk.unsupported/sun.misc.Unsafe.invokeCleaner(Unsafe.java:1238) ... 17 common frames omitted

As a consequence, it looks like old journal files are not reclaimed and consumption of disk space grows indefinitely.
Tested using OpenJDK 11.