Intermittent NullPointerException during upgrade for polling to websocket

[cbdwan]

Occasionally getting this NPE during the upgrade from polling to websockt, it looks like it happens if the upgrade is happening just after a poll request has been done and before the next one comes in to set the mPollRequest.

Dont have a reproducible testcase for this.

This with version 1.3.5.

java.lang.NullPointerException: null
at io.socket.engineio.server.transport.Polling.send(Polling.java:82) ~[engine.io-server-1.3.5.jar:?]
at io.socket.engineio.server.EngineIoSocket.lambda$upgrade$4(EngineIoSocket.java:174) ~[engine.io-server-1.3.5.jar:?]
at io.socket.emitter.Emitter.emit(Emitter.java:117) ~[engine.io-client-1.0.0.jar:?]
at io.socket.engineio.server.Transport.onPacket(Transport.java:87) ~[engine.io-server-1.3.5.jar:?]
at io.socket.engineio.server.Transport.onData(Transport.java:96) ~[engine.io-server-1.3.5.jar:?]
at io.socket.engineio.server.transport.WebSocket.lambda$new$0(WebSocket.java:25) ~[engine.io-server-1.3.5.jar:?]
at io.socket.emitter.Emitter.emit(Emitter.java:117) ~[engine.io-client-1.0.0.jar:?]
at com.bcdfx.web.ws.EngineIoEndpoint$1.onMessage(EngineIoEndpoint.java:67) ~[classes/:4.8.0]
at com.bcdfx.web.ws.EngineIoEndpoint$1.onMessage(EngineIoEndpoint.java:63) ~[classes/:4.8.0]
at org.apache.tomcat.websocket.WsFrameBase.sendMessageText(WsFrameBase.java:394) [tomcat-websocket.jar:8.5.49]
at org.apache.tomcat.websocket.server.WsFrameServer.sendMessageText(WsFrameServer.java:119) [tomcat-websocket.jar:8.5.49]
at org.apache.tomcat.websocket.WsFrameBase.processDataText(WsFrameBase.java:495) [tomcat-websocket.jar:8.5.49]
at org.apache.tomcat.websocket.WsFrameBase.processData(WsFrameBase.java:294) [tomcat-websocket.jar:8.5.49]
at org.apache.tomcat.websocket.WsFrameBase.processInputBuffer(WsFrameBase.java:133) [tomcat-websocket.jar:8.5.49]
at org.apache.tomcat.websocket.server.WsFrameServer.onDataAvailable(WsFrameServer.java:82) [tomcat-websocket.jar:8.5.49]
at org.apache.tomcat.websocket.server.WsFrameServer.doOnDataAvailable(WsFrameServer.java:171) [tomcat-websocket.jar:8.5.49]
at org.apache.tomcat.websocket.server.WsFrameServer.notifyDataAvailable(WsFrameServer.java:151) [tomcat-websocket.jar:8.5.49]
at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler.upgradeDispatch(WsHttpUpgradeHandler.java:148) [tomcat-websocket.jar:8.5.49]
at org.apache.coyote.http11.upgrade.UpgradeProcessorInternal.dispatch(UpgradeProcessorInternal.java:54) [tomcat-coyote.jar:8.5.49]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:59) [tomcat-coyote.jar:8.5.49]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:810) [tomcat-coyote.jar:8.5.49]
at org.apache.tomcat.util.net.Nio2Endpoint$SocketProcessor.doRun(Nio2Endpoint.java:1783) [tomcat-coyote.jar:8.5.49]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-coyote.jar:8.5.49]
at org.apache.tomcat.util.net.AbstractEndpoint.processSocket(AbstractEndpoint.java:1082) [tomcat-coyote.jar:8.5.49]
at org.apache.tomcat.util.net.Nio2Endpoint$Nio2SocketWrapper$2.completed(Nio2Endpoint.java:569) [tomcat-coyote.jar:8.5.49]
at org.apache.tomcat.util.net.Nio2Endpoint$Nio2SocketWrapper$2.completed(Nio2Endpoint.java:547) [tomcat-coyote.jar:8.5.49]
at org.apache.tomcat.util.net.SecureNio2Channel$1.completed(SecureNio2Channel.java:969) [tomcat-coyote.jar:8.5.49]
at org.apache.tomcat.util.net.SecureNio2Channel$1.completed(SecureNio2Channel.java:898) [tomcat-coyote.jar:8.5.49]
at sun.nio.ch.Invoker.invokeUnchecked(Invoker.java:127) [?:?]
at sun.nio.ch.Invoker$2.run(Invoker.java:219) [?:?]
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(AsynchronousChannelGroupImpl.java:112) [?:?]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630) [?:?]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.5.49]
at java.lang.Thread.run(Thread.java:832) [?:?]

[trinopoty]

I've noticed this as well. A fix is on the way.

[trinopoty]

Can you update to v5.0.0 of the library and check if this issue is still there. v5 is fully backwards compatible with v1.