In a clustering test, I observed the following exception happening during server shutdown: 10:34:12,373 ERROR [org.apache.catalina.connector] (ajp-perf18/10.16.90.54:8009-22) JBWEB001018: An exception or error occurred in the container during the request processing: java.lang.NullPointerException at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:336) [jbossweb-7.2.1.Final-redhat-1.jar:7.2.1.Final-redhat-1] at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:488) [jbossweb-7.2.1.Final-redhat-1.jar:7.2.1.Final-redhat-1] at org.apache.coyote.ajp.AjpProtocol$AjpConnectionHandler.process(AjpProtocol.java:420) [jbossweb-7.2.1.Final-redhat-1.jar:7.2.1.Final-redhat-1] at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:920) [jbossweb-7.2.1.Final-redhat-1.jar:7.2.1.Final-redhat-1] at java.lang.Thread.run(Thread.java:662) [rt.jar:1.6.0_45] See the log file: https://jenkins.mw.lab.eng.bos.redhat.com/hudson/job/eap-6x-failover-ejb-ejbservlet-shutdown-dist-async/12/console-perf18/
Update: this was last seen in EAP 6.3.0.DR2. I don't know if this wasn't fixed in the meantime, but if it wasn't, it's very, very rare.