Atmosphere errors

I still get a few of these each day.  No user impact that I can find.  Does anyone know the cause?  I use the latest Vaadin (7.5.6), Tomcat (8.0.27), Java (8 u60).  I'm guessing that this is a bug in Tomcat, but wonder if Vaadin experts recognize it?

Oct 04, 2015 12:41:43 PM org.atmosphere.container.JSR356Endpoint onError
SEVERE: 
java.io.IOException: Unexpected error [104] reading data from the APR/native socket [139,884,467,731,680] with wrapper [org.apache.tomcat.util.net.AprEndpoint$AprSocketWrapper@23565260:139884467731680].
    at org.apache.coyote.http11.upgrade.AprServletInputStream.doRead(AprServletInputStream.java:133)
    at org.apache.coyote.http11.upgrade.AbstractServletInputStream.read(AbstractServletInputStream.java:124)
    at org.apache.tomcat.websocket.server.WsFrameServer.onDataAvailable(WsFrameServer.java:51)
    at org.apache.tomcat.websocket.server.WsHttpUpgradeHandler$WsReadListener.onDataAvailable(WsHttpUpgradeHandler.java:203)
    at org.apache.coyote.http11.upgrade.AbstractServletInputStream.onDataAvailable(AbstractServletInputStream.java:198)
    at org.apache.coyote.http11.upgrade.AbstractProcessor.upgradeDispatch(AbstractProcessor.java:96)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2503)
    at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2492)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

Oct 04, 2015 12:41:43 PM com.vaadin.server.communication.PushHandler connectionLost
INFO: No UI was found based on data in the request, but a slower lookup based on the AtmosphereResource succeeded. See http://dev.vaadin.com/ticket/14251 for more details.

I've got same error with Vaadin 7.7.1, Tomcat 8.0.33 Java 8 u45 but I have an apache2 proxy.

I do not have the log INFO

com.vaadin.server.communication.PushHandler connectionLost

I would like to know if Atmosphere errors could be related to  "Session Expiry" 

On the user side I'm using push and I see quite often "Session Expiry" messages but I do not know if it is related to above error.
Browser logs do not show any communication problems so it seems that heartbeat has been really missed.

I'm using closeIdleSessions=false so I'm not expecting "Session Expiry" if user does not interact with page

these are relevant parts from my web.xml

<init-param>
              <param-name>closeIdleSessions</param-name>
              <param-value>false</param-value>
        </init-param>

           <init-param>
              <param-name>pushmode</param-name>
              <param-value>manual</param-value>
        </init-param>
        
          <async-supported>true</async-supported>      

    <context-param>
        <param-name>heartbeatInterval</param-name>
        <param-value>300</param-value>
    </context-param>

    <session-config>
        <session-timeout>30</session-timeout>
    </session-config>

How did you solve this problem?

I'm still living with a log full of these stack traces. There's no known harm other than log pollution, but it would be nice if these exceptions could be caught or muted without hiding any similar exception that may need attention.