Crowd never stops properly leaving the Java process hanging...

Upon issuing the ./stop_crowd.sh command Crowd stops serving requests but the Java process is left hanging...

catalina.out

Aug 14, 2015 4:41:46 PM org.apache.catalina.core.StandardServer await
INFO: A valid shutdown command was received via the shutdown port. Stopping the Server instance.
Aug 14, 2015 4:41:46 PM org.apache.coyote.AbstractProtocol pause
INFO: Pausing ProtocolHandler ["http-bio-8020"]
Aug 14, 2015 4:41:46 PM org.apache.coyote.AbstractProtocol pause
INFO: Pausing ProtocolHandler ["http-bio-8021"]
Aug 14, 2015 4:41:46 PM org.apache.catalina.core.StandardService stopInternal
INFO: Stopping service Catalina
2015-08-14 16:41:46,965 localhost-startStop-2 INFO [ContainerBase.[Catalina].[localhost].[/crowd]] org.tuckey.web.filters.urlrewrite.UrlRewriteFilter INFO: destroy called
2015-08-14 16:41:46,969 localhost-startStop-2 INFO [ContainerBase.[Catalina].[localhost].[/crowd]] Closing Spring root WebApplicationContext
2015-08-14 16:41:47,015 localhost-startStop-2 INFO [com.atlassian.crowd.startup] Stopping Crowd
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/crowd] 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.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/crowd] 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.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/crowd] 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.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/crowd] appears to have started a thread named [scheduler_Worker-4] but has failed to stop it. This is very likely to create a memory leak.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/crowd] appears to have started a thread named [scheduler_Worker-5] but has failed to stop it. This is very likely to create a memory leak.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/crowd] 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.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/crowd] 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.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/crowd] 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.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/crowd] appears to have started a thread named [scheduler_Worker-9] but has failed to stop it. This is very likely to create a memory leak.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/crowd] 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.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader checkThreadLocalMapForLeaks
SEVERE: The web application [/crowd] created a ThreadLocal with key of type [java.lang.InheritableThreadLocal] (value [java.lang.InheritableThreadLocal@6c0fb5c3]) and a value of type [org.apache.felix.framework.BundleContextImpl] (value [org.apache.felix.framework.BundleContextImpl@2ffae255]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.
Shutting down spray application ...
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/openidserver] appears to have started a thread named [HSQLDB Timer @a54f8e3] but has failed to stop it. This is very likely to create a memory leak.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader checkThreadLocalMapForLeaks
SEVERE: The web application [/openidserver] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@63483046]) and a value of type [scala.concurrent.forkjoin.ForkJoinPool.Submitter] (value [scala.concurrent.forkjoin.ForkJoinPool$Submitter@7d79fbb5]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.
Aug 14, 2015 4:41:47 PM org.apache.catalina.loader.WebappClassLoader checkThreadLocalMapForLeaks
SEVERE: The web application [/openidserver] created a ThreadLocal with key of type [scala.util.DynamicVariable$$anon$1] (value [scala.util.DynamicVariable$$anon$1@5f112e5c]) and a value of type [org.apache.tomcat.util.log.SystemLogHandler] (value [org.apache.tomcat.util.log.SystemLogHandler@4459ead2]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.
Aug 14, 2015 4:41:47 PM org.apache.coyote.AbstractProtocol stop
INFO: Stopping ProtocolHandler ["http-bio-8020"]
Aug 14, 2015 4:41:47 PM org.apache.coyote.AbstractProtocol stop
INFO: Stopping ProtocolHandler ["http-bio-8021"]
Aug 14, 2015 4:41:47 PM org.apache.coyote.AbstractProtocol destroy
INFO: Destroying ProtocolHandler ["http-bio-8020"]
Aug 14, 2015 4:41:47 PM org.apache.coyote.AbstractProtocol destroy
INFO: Destroying ProtocolHandler ["http-bio-8021"]