Rajat Goel created KNOX-1997:
--------------------------------
Summary: For websocket connections, seeing
java.lang.NullPointerException when a data frame arrives on websocket while
connection is still being setup
Key: KNOX-1997
URL: https://issues.apache.org/jira/browse/KNOX-1997
Project: Apache Knox
Issue Type: Bug
Components: Server
Affects Versions: 1.0.0
Environment: HDP 3.1.0
Reporter: Rajat Goel
Attachments: gateway.log_26Aug.gz
I am seeing following exception in Knox gateway logs:
_2019-08-23 12:43:46,347 WARN websockets.ProxyInboundClient
(AbstractEventDriver.java:unhandled(251)) - Unhandled Error (closing
connection)_
_java.lang.NullPointerException_
_at
org.apache.knox.gateway.websockets.ProxyWebSocketAdapter$3.onMessageText(ProxyWebSocketAdapter.java:260)_
_at
org.apache.knox.gateway.websockets.ProxyInboundClient$2.onMessage(ProxyInboundClient.java:87)_
_at
org.apache.knox.gateway.websockets.ProxyInboundClient$2.onMessage(ProxyInboundClient.java:78)_
_at
org.eclipse.jetty.websocket.jsr356.messages.TextWholeMessage.messageComplete(TextWholeMessage.java:56)_
_at
org.eclipse.jetty.websocket.jsr356.endpoints.JsrEndpointEventDriver.onTextFrame(JsrEndpointEventDriver.java:218)_
_at
org.eclipse.jetty.websocket.common.events.AbstractEventDriver.incomingFrame(AbstractEventDriver.java:162)_
_at
org.eclipse.jetty.websocket.common.WebSocketSession.incomingFrame(WebSocketSession.java:476)_
_at
org.eclipse.jetty.websocket.common.extensions.ExtensionStack.incomingFrame(ExtensionStack.java:220)_
_at org.eclipse.jetty.websocket.common.Parser.notifyFrame(Parser.java:219)_
_at org.eclipse.jetty.websocket.common.Parser.parse(Parser.java:244)_
_at
org.eclipse.jetty.websocket.common.io.AbstractWebSocketConnection.onConnectionStateChange(AbstractWebSocketConnection.java:337)_
_at
org.eclipse.jetty.websocket.common.io.IOState.notifyStateListeners(IOState.java:184)_
_at org.eclipse.jetty.websocket.common.io.IOState.onOpened(IOState.java:447)_
_at
org.eclipse.jetty.websocket.common.WebSocketSession.open(WebSocketSession.java:619)_
_at
org.eclipse.jetty.websocket.common.WebSocketSession.onOpened(WebSocketSession.java:544)_
_at
org.eclipse.jetty.io.AbstractConnection.onOpened(AbstractConnection.java:209)_
_at org.eclipse.jetty.io.AbstractConnection.onOpen(AbstractConnection.java:202)_
_at
org.eclipse.jetty.websocket.common.io.AbstractWebSocketConnection.onOpen(AbstractWebSocketConnection.java:446)_
_at org.eclipse.jetty.io.AbstractEndPoint.upgrade(AbstractEndPoint.java:440)_
_at
org.eclipse.jetty.websocket.client.WebSocketUpgradeRequest.upgrade(WebSocketUpgradeRequest.java:624)_
_at
org.eclipse.jetty.client.http.HttpChannelOverHTTP.exchangeTerminating(HttpChannelOverHTTP.java:118)_
_at
org.eclipse.jetty.client.HttpReceiver.terminateResponse(HttpReceiver.java:462)_
_at
org.eclipse.jetty.client.HttpReceiver.responseSuccess(HttpReceiver.java:416)_
I added more debug logs in Knox to analyze the issue and observed following was
happening:
* Knox generates proper URL for backend websocket connection
_2019-08-23 12:43:46,068 DEBUG gateway.websockets
(GatewayWebsocketHandler.java:createWebSocket(148)) - Message: Rajat ..
backednUrl =
ws://[rafd001-mst-01.cloud.in.guavus.com:11011/_sock/411/anq2kfzp/websocket|http://rafd001-mst-01.cloud.in.guavus.com:11011/_sock/411/anq2kfzp/websocket]_
* Websocket upgrade successful at HTTP protocol layer. Knox starts setting up
its session management internal data structures for this connection
_2019-08-23 12:43:46,313 DEBUG client.HttpReceiver
(HttpReceiver.java:responseSuccess(403)) - Response success
HttpResponse[HTTP/1.1 101 Switching Protocols]@708f1c60_
_2019-08-23 12:43:46,324 DEBUG common.WebSocketSession
(WebSocketSession.java:doStart(248)) - starting -
WebSocketSession[websocket=JsrEndpointEventDriver[org.apache.knox.gateway.websockets.ProxyInboundClient],behavior=CLIENT,connection=WebSocketClientConnection@1528d316::SocketChannelEndPoint@10d45033
{[rafd001-mst-01.cloud.in.guavus.com/192.168.133.69:11011|http://rafd001-mst-01.cloud.in.guavus.com/192.168.133.69:11011]<->/[192.168.133.69:50702|http://192.168.133.69:50702/],OPEN,fill=-,flush=-,to=23/300000}
\{io=0/0,kio=0,kro=1} >
r:[rafd001-mst-01.cloud.in.guavus.com/192.168.133.69:11011,closed=false)=|http://rafd001-mst-01.cloud.in.guavus.com/192.168.133.69:11011,closed=false)=]>HttpChannelOverHTTP@26de2594(exchange=HttpExchange@7e8b6268
req=TERMINATED/null@null
res=TERMINATED/null@null)[send=HttpSenderOverHTTP@73b692d4(req=QUEUED,snd=COMPLETED,failure=null)[HttpGenerator@4e3bb764\{s=START}],recv=HttpReceiverOverHTTP@7d5a172b(rsp=IDLE,failure=null)[HttpParser\{s=START,0
of1}]],remote=null,incoming=JsrEndpointEventDriver[org.apache.knox.gateway.websockets.ProxyInboundClient],outgoing=ExtensionStack[queueSize=0,extensions=[],incoming=org.eclipse.jetty.websocket.jsr356.JsrSession,outgoing=org.eclipse.jetty.websocket.client.io.WebSocketClientConnection]]_
* A data frame arrives on the connection from CDAP backend and Knox starts
processing it in a separate thread but internal data structures have not yet
been established fully:
_2019-08-23 12:43:46,346 DEBUG gateway.websockets
(ProxyWebSocketAdapter.java:onMessageText(257)) - Message: Rajat .. In
onMessageText .. remote is nulll_
_2019-08-23 12:43:46,347 WARN websockets.ProxyInboundClient
(AbstractEventDriver.java:unhandled(251)) - Unhandled Error (closing
connection)_
_java.lang.NullPointerException_
_at
org.apache.knox.gateway.websockets.ProxyWebSocketAdapter$3.onMessageText(ProxyWebSocketAdapter.java:260)_
_at
org.apache.knox.gateway.websockets.ProxyInboundClient$2.onMessage(ProxyInboundClient.java:87)_
_at
org.apache.knox.gateway.websockets.ProxyInboundClient$2.onMessage(ProxyInboundClient.java:78)_
* As a result of this exception, Knox starts closing this connection as well
as connection with front end.
_2019-08-23 12:43:46,347 DEBUG gateway.websockets
(ProxyWebSocketAdapter.java:onError(246)) - Message: Rajat .. inside onError_
_2019-08-23 12:43:46,348 DEBUG gateway.websockets
(ProxyWebSocketAdapter.java:cleanupOnError(183)) - Message: Rajat .. inside
cleanupOnError_
_2019-08-23 12:43:46,348 ERROR gateway.websockets
(ProxyWebSocketAdapter.java:cleanupOnError(185)) - Error:
java.lang.NullPointerException_
_2019-08-23 12:43:46,349 DEBUG gateway.websockets
(ProxyWebSocketAdapter.java:closeQuietly(294)) - Message: Rajat .. in
closeQuietly_
* Internal data structures are now setup in the other thread
_2019-08-23 12:43:46,356 DEBUG gateway.websockets
(ProxyWebSocketAdapter.java:onWebSocketConnect(113)) - Message: Rajat ...
frontEndSession =
WebSocketSession[websocket=JettyListenerEventDriver[org.apache.knox.gateway.websockets.ProxyWebSocketAdapter],behavior=SERVER,connection=WebSocketServerConnection@151585ba::DecryptedEndPoint@4463419a
{/[192.168.110.254:61755|http://192.168.110.254:61755/]<>/[192.168.133.69:8443|http://192.168.133.69:8443/],OPEN,fill=,flush=,to=423/300000},remote=WebSocketRemoteEndpoint@66632a26[batching=true],incoming=JettyListenerEventDriver[org.apache.knox.gateway.websockets.ProxyWebSocketAdapter],outgoing=ExtensionStack[queueSize=0,extensions=[permessage-deflate],incoming=org.eclipse.jetty.websocket.common.extensions.compress.PerMessageDeflateExtension,outgoing=org.eclipse.jetty.websocket.common.extensions.compress.PerMessageDeflateExtension]]_
_2019-08-23 12:43:46,358 DEBUG gateway.websockets
(ProxyWebSocketAdapter.java:onWebSocketConnect(119)) - Message: Rajat ...front
remote = WebSocketRemoteEndpoint@66632a26[batching=true]_
* Fronted UI sees connection closed and send a new connection request.
Looks like there is a race condition/improper synchronization between two Knox
threads: one thread opening a websocket connection, setting up the connection
session and the other thread processing a message/data packet sent by UI
service backend.
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