AMQ broker becomes slow and clients cannot connect

Issue

• AMQ broker becomes slow
• Finally, the client is unable to connect to the broker due to a timeout error.

2018-06-22 09:26:14,048 ERROR [org.apache.activemq.artemis.core.server] AMQ224088: Timeout (10 seconds) while handshaking has occurred.

2018-06-22 09:26:14,049 WARN  [io.netty.util.concurrent.DefaultPromise] An exception was thrown by org.apache.activemq.artemis.core.remoting.impl.netty.SharedEventLoopGroup$2$1.operationComplete(): java.lang.IllegalStateException: complete already: ImmediateEventExecutor$ImmediatePromise@2845eb7e(success)
        at io.netty.util.concurrent.DefaultPromise.setSuccess(DefaultPromise.java:98) [netty-all-4.1.16.Final-redhat-2.jar:4.1.16.Final-redhat-2]
        at org.apache.activemq.artemis.core.remoting.impl.netty.SharedEventLoopGroup$2$1.operationComplete(SharedEventLoopGroup.java:98) [artemis-core-client-2.4.0.amq-711002-redhat-1.jar:2.4.0.amq-711002-redhat-1]