NPE at InternalNioOutputBuffer.addToBB() in Tomcat 7

[masoncj]

When writing a response from a serializer using tomcat 7.0.32 in a long polling async servlet 3.0 setup, I see the follow exception fairly frequently (but not every time). I came across this post which suggests it might either be a synchronization problem or a async request that has already terminated. This is with atmosphere 1.0.x at rev ac04315.

The code is basically:

resource.setSerializer(new Serializer() {
            @Override
            public void write(OutputStream os, Object message) throws IOException {
                    String serialized = jackson.serializeToJson(message);
                    os.write(serialized);
                    os.flush();
             }
});

Should I:

• not be calling flush? Am I ensured the data I write gets back to the client without the flush?
• be synchronizing this somehow? How?

java.lang.NullPointerException
    at org.apache.coyote.http11.InternalNioOutputBuffer.addToBB(InternalNioOutputBuffer.java:210)
    at org.apache.coyote.http11.InternalNioOutputBuffer.commit(InternalNioOutputBuffer.java:202)
    at org.apache.coyote.http11.AbstractHttp11Processor.action(AbstractHttp11Processor.java:765)
    at org.apache.coyote.Response.action(Response.java:174)
    at org.apache.coyote.Response.sendHeaders(Response.java:354)
    at org.apache.catalina.connector.OutputBuffer.doFlush(OutputBuffer.java:330)
    at org.apache.catalina.connector.OutputBuffer.flush(OutputBuffer.java:306)
    at org.apache.catalina.connector.CoyoteOutputStream.flush(CoyoteOutputStream.java:101)
    at org.codehaus.jackson.impl.Utf8Generator.flush(Utf8Generator.java:1091)
    at org.codehaus.jackson.map.ObjectWriter.writeValue(ObjectWriter.java:328)
    at com.thetus.platforms.savanna.components.job.service.JobServiceRestController$1.write(JobServiceRestController.java:131)
    at org.atmosphere.handler.AbstractReflectorAtmosphereHandler.onStateChange(AbstractReflectorAtmosphereHandler.java:101)
    at org.atmosphere.cpr.DefaultBroadcaster.invokeOnStateChange(DefaultBroadcaster.java:1012)
    at org.atmosphere.cpr.DefaultBroadcaster.executeAsyncWrite(DefaultBroadcaster.java:936)
    at org.atmosphere.cpr.DefaultBroadcaster$3.run(DefaultBroadcaster.java:583)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
    at java.util.concurrent.FutureTask.run(FutureTask.java:138)
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
    at java.lang.Thread.run(Thread.java:680)

[jfarcand]

Salut, I suspect the connection has already been resumed and the second call to that resource is causing this issue. The exception will be logged but your application should still work IMO. Is it the case?

[jfarcand]

I don't think that is cause issue. Just let Atmosphere recover itself from that exception (the message will be cached). Thanks!