Warning messages after server starts

[Dave Mallick]

After the server starts, there are a number of warning messages in the log files. How do I fix them?

Warning message:

27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [ROOT] registered the JDBC driver [org.h2.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [ROOT] registered the JDBC driver [org.hsqldb.jdbc.JDBCDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [ROOT] registered the JDBC driver [net.sourceforge.jtds.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [ROOT] registered the JDBC driver [com.github.gquintana.metrics.sql.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [ROOT] registered the JDBC driver [com.microsoft.sqlserver.jdbc.SQLServerDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [ROOT] registered the JDBC driver [org.postgresql.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [scheduler_Worker-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/java.lang.Object.wait(Native Method)
org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:543)
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [scheduler_Worker-2] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/java.lang.Object.wait(Native Method)
org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:543)
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [scheduler_Worker-3] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/java.lang.Object.wait(Native Method)
org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:543)
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [scheduler_Worker-6] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/java.lang.Object.wait(Native Method)
org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:543)
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [scheduler_Worker-7] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/java.lang.Object.wait(Native Method)
org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:543)
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [scheduler_Worker-8] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/java.lang.Object.wait(Native Method)
org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:543)
27-Dec-2020 06:06:02.531 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [scheduler_Worker-10] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/java.lang.Object.wait(Native Method)
org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:543)
27-Dec-2020 06:06:02.546 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [AtlassianEvent::CustomizableThreadFactory-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/jdk.internal.misc.Unsafe.park(Native Method)
java.base@11.0.8/java.util.concurrent.locks.LockSupport.park(Unknown Source)
java.base@11.0.8/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(Unknown Source)
java.base@11.0.8/java.util.concurrent.LinkedBlockingQueue.take(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
java.base@11.0.8/java.lang.Thread.run(Unknown Source)
27-Dec-2020 06:06:02.546 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [AtlassianEvent::CustomizableThreadFactory-2] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/jdk.internal.misc.Unsafe.park(Native Method)
java.base@11.0.8/java.util.concurrent.locks.LockSupport.park(Unknown Source)
java.base@11.0.8/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(Unknown Source)
java.base@11.0.8/java.util.concurrent.LinkedBlockingQueue.take(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
java.base@11.0.8/java.lang.Thread.run(Unknown Source)
27-Dec-2020 06:06:02.546 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [atlassian-webhooks-scheduler:thread-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/jdk.internal.misc.Unsafe.park(Native Method)
java.base@11.0.8/java.util.concurrent.locks.LockSupport.parkNanos(Unknown Source)
java.base@11.0.8/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(Unknown Source)
java.base@11.0.8/java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(Unknown Source)
java.base@11.0.8/java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
java.base@11.0.8/java.lang.Thread.run(Unknown Source)
27-Dec-2020 06:06:02.546 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [atlassian-instrumentation-jmx:thread-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/jdk.internal.misc.Unsafe.park(Native Method)
java.base@11.0.8/java.util.concurrent.locks.LockSupport.parkNanos(Unknown Source)
java.base@11.0.8/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(Unknown Source)
java.base@11.0.8/java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(Unknown Source)
java.base@11.0.8/java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
java.base@11.0.8/java.lang.Thread.run(Unknown Source)
27-Dec-2020 06:06:02.546 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [process-utils:idle] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/jdk.internal.misc.Unsafe.park(Native Method)
java.base@11.0.8/java.util.concurrent.locks.LockSupport.park(Unknown Source)
java.base@11.0.8/java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(Unknown Source)
java.base@11.0.8/java.util.concurrent.SynchronousQueue$TransferStack.transfer(Unknown Source)
java.base@11.0.8/java.util.concurrent.SynchronousQueue.take(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
java.base@11.0.8/java.lang.Thread.run(Unknown Source)
27-Dec-2020 06:06:02.546 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [process-utils:idle] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/jdk.internal.misc.Unsafe.park(Native Method)
java.base@11.0.8/java.util.concurrent.locks.LockSupport.park(Unknown Source)
java.base@11.0.8/java.util.concurrent.SynchronousQueue$TransferStack.awaitFulfill(Unknown Source)
java.base@11.0.8/java.util.concurrent.SynchronousQueue$TransferStack.transfer(Unknown Source)
java.base@11.0.8/java.util.concurrent.SynchronousQueue.take(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.getTask(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.base@11.0.8/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
java.base@11.0.8/java.lang.Thread.run(Unknown Source)
27-Dec-2020 06:06:02.546 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [Caesium-1-1] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/jdk.internal.misc.Unsafe.park(Native Method)
java.base@11.0.8/java.util.concurrent.locks.LockSupport.park(Unknown Source)
java.base@11.0.8/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(Unknown Source)
com.atlassian.scheduler.caesium.impl.SchedulerQueueImpl.takeUnderLock(SchedulerQueueImpl.java:292)
com.atlassian.scheduler.caesium.impl.SchedulerQueueImpl.take(SchedulerQueueImpl.java:246)
com.atlassian.scheduler.caesium.impl.SchedulerQueueWorker.executeNextJob(SchedulerQueueWorker.java:54)
com.atlassian.scheduler.caesium.impl.SchedulerQueueWorker.run(SchedulerQueueWorker.java:35)
java.base@11.0.8/java.lang.Thread.run(Unknown Source)
27-Dec-2020 06:06:02.546 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [Caesium-1-2] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/jdk.internal.misc.Unsafe.park(Native Method)
java.base@11.0.8/java.util.concurrent.locks.LockSupport.park(Unknown Source)
java.base@11.0.8/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(Unknown Source)
com.atlassian.scheduler.caesium.impl.SchedulerQueueImpl.takeUnderLock(SchedulerQueueImpl.java:292)
com.atlassian.scheduler.caesium.impl.SchedulerQueueImpl.take(SchedulerQueueImpl.java:246)
com.atlassian.scheduler.caesium.impl.SchedulerQueueWorker.executeNextJob(SchedulerQueueWorker.java:54)
com.atlassian.scheduler.caesium.impl.SchedulerQueueWorker.run(SchedulerQueueWorker.java:35)
java.base@11.0.8/java.lang.Thread.run(Unknown Source)
27-Dec-2020 06:06:02.546 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [Caesium-1-3] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/jdk.internal.misc.Unsafe.park(Native Method)
java.base@11.0.8/java.util.concurrent.locks.LockSupport.park(Unknown Source)
java.base@11.0.8/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(Unknown Source)
com.atlassian.scheduler.caesium.impl.SchedulerQueueImpl.takeUnderLock(SchedulerQueueImpl.java:292)
com.atlassian.scheduler.caesium.impl.SchedulerQueueImpl.take(SchedulerQueueImpl.java:246)
com.atlassian.scheduler.caesium.impl.SchedulerQueueWorker.executeNextJob(SchedulerQueueWorker.java:54)
com.atlassian.scheduler.caesium.impl.SchedulerQueueWorker.run(SchedulerQueueWorker.java:35)
java.base@11.0.8/java.lang.Thread.run(Unknown Source)
27-Dec-2020 06:06:02.546 WARNING [Catalina-utility-1] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [ROOT] appears to have started a thread named [Caesium-1-4] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.base@11.0.8/jdk.internal.misc.Unsafe.park(Native Method)
java.base@11.0.8/java.util.concurrent.locks.LockSupport.park(Unknown Source)
java.base@11.0.8/java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(Unknown Source)
com.atlassian.scheduler.caesium.impl.SchedulerQueueImpl.takeUnderLock(SchedulerQueueImpl.java:292)
com.atlassian.scheduler.caesium.impl.SchedulerQueueImpl.take(SchedulerQueueImpl.java:246)
com.atlassian.scheduler.caesium.impl.SchedulerQueueWorker.executeNextJob(SchedulerQueueWorker.java:54)
com.atlassian.scheduler.caesium.impl.SchedulerQueueWorker.run(SchedulerQueueWorker.java:35)
java.base@11.0.8/java.lang.Thread.run(Unknown Source)

[Daniel Ebers]

Hi @Dave Mallick

bad news first: they are so generic it is not possible to tell you right now to "push the red button and everything will be okay".

Does the error messages hinder Confluence in starting properly?
I am asking because there are reports in Community that this is the case. As soon as users had those warnings nothing worked anymore.

In case it is just a warning it is less critical.

Are you using an embedded H2 database? The messages suggest that. This database type is just for evaluation purposes and it is reported to be picky.

Regards,
Daniel