Caused by: java.lang.IllegalStateException: Concurrent write operations are not permitted
	at org.apache.tomcat.websocket.AsyncChannelWrapperSecure.write(AsyncChannelWrapperSecure.java:116)
	at org.apache.tomcat.websocket.WsRemoteEndpointImplClient.doWrite(WsRemoteEndpointImplClient.java:62)
	at org.apache.tomcat.websocket.WsRemoteEndpointImplBase$OutputBufferSendHandler.write(WsRemoteEndpointImplBase.java:864)
	at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.writeMessagePart(WsRemoteEndpointImplBase.java:491)
	at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendMessageBlock(WsRemoteEndpointImplBase.java:309)
	at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendMessageBlock(WsRemoteEndpointImplBase.java:258)
	at org.apache.tomcat.websocket.WsSession.sendCloseMessage(WsSession.java:606)
	at org.apache.tomcat.websocket.WsSession.doClose(WsSession.java:494)
	at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendMessageBlock(WsRemoteEndpointImplBase.java:313)
	at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendMessageBlock(WsRemoteEndpointImplBase.java:250)
	at org.apache.tomcat.websocket.WsRemoteEndpointImplBase.sendString(WsRemoteEndpointImplBase.java:191)
	at org.apache.tomcat.websocket.WsRemoteEndpointBasic.sendText(WsRemoteEndpointBasic.java:37)
        at ...