Re: [xSocket-develop] ClosedChannelException

[Gregor R. <gre...@go...>]

Hi David,

you bug can be the reason for the closed channel. If the onData implemention
throws an exception, xSocket will close the underlying connection. Please
re-run your test based on your fixed code.

Gregor

2008/11/5 David Alves <da...@st...>

> Hi
> Thanks for your insight Gregor.
> Indeed I was wodering why the readStringByDelimiter was returning a
> bytebuffer[] since in every case I tested the array only seemed to contain
> one element. I'll update my code as you sugest regarding this, and regarding
> the data serialization issue.
> But, correct me if I'm mistaken, that doesn't explain why the client always
> throws a ClosedChannelException after 67 object serializations, right?
> Any ideas as to why this is happening?
>
> Regards
> David Alves
>
> On Nov 5, 2008, at 7:08 AM, Gregor Roth wrote:
>
> Hi David,
>
> the <connection>.readByteBufferByDelimiter(…) returns an array of byte
> buffers. This doesn't mean, that several records (separated by a delimiter)
> is fetched. If you get an array longer than 1, it just means that more than
> one byte buffer is used to hold the record data. This is caused by a
> fragmented network I/O read. For performance reasons xSocket doesn't merge
> such fragmented byte buffers into a single buffer. xSocket's DataConverter
> class supports a toByteBuffer(ByteBuffer[] buffers) method to do this (which
> has performance impacts).
>
> In your code you have also to ensure that your delimiter will never appear
> as part of the serialized data. May be using a leading length filed would be
> a better approach
>
> Gregor
>
>
>
>
> 2008/11/5 David Alves <da...@st...>
>
>> Hi
>> I'm trying xsocket for the first time and I quite like the api and the
>> features.
>> I'm using a nonblockingpipeline over a multiplexed connection and all
>> seems fine, until the channel closes and a ClosedChannelException is thrown.
>>  I'm reasearching some event processing mechanisms and as such I
>> serialize objects across the client to the server, and it all boils down to
>> the fact that I always can send 67 and just 67 events.
>>  Strange no?
>> Any help would be greatly appreciated.
>> My send/receive code along with the trace is in the end of the email.
>>
>> Kind regards
>> David Alves
>>
>> ______________________
>>
>> Client: (All the connection creation code is done only once then a
>> generating thread tries to send event through the pipeline)
>>
>> Creation:
>> this.nativeConnection = new NonBlockingConnection(this.host, port,
>> Integer.MAX_VALUE);
>>  this.multiplexedConnection = new MultiplexedConnection(nativeConnection
>> );
>>  controlPipelineId = multiplexedConnection.createPipeline();
>>  controlPipeline = multiplexedConnection.getNonBlockingPipeline(
>> controlPipelineId);
>>
>> Repeat:
>> FastByteArrayOutputStream fbaos = new FastByteArrayOutputStream();
>>  ObjectOutputStream oos = new ObjectOutputStream(fbaos);
>> oos.writeObject(event);
>>  ByteBuffer objectBuffer = fbaos.getByteBuffer();
>> controlPipeline.write(objectBuffer);
>>  controlPipeline.write(EVENT_SEPARATOR);
>>
>> ________________
>>
>>    Server: (Implements IPipelineDataHandler)
>> ByteBuffer[] eventsBbs = pipeline
>>  .readByteBufferByDelimiter(DummyMultiplexedNonBockingAdapter.
>> EVENT_SEPARATOR);
>>  for (ByteBuffer eventBb : eventsBbs) {
>> FastByteArrayInputStream fbais = new FastByteArrayInputStream(eventBb);
>>  ObjectInputStream ois = new ObjectInputStream(fbais);
>> Event event;
>>  try {
>> event = (Event) ois.readObject();
>>  } catch (ClassNotFoundException e) {
>> throw new IOException(e);
>>  }
>> receiveEvent(event);
>> }
>>
>> Trace:
>>
>> Caused by: java.nio.channels.ClosedChannelException
>>  at
>> org.xsocket.connection.AbstractNonBlockingStream.ensureStreamIsOpenAndWritable(
>> AbstractNonBlockingStream.java:1472)
>>  at org.xsocket.connection.AbstractNonBlockingStream.write(
>> AbstractNonBlockingStream.java:1140)
>>  at
>> pt.uc.dei.fincos.adapter.dummy.remote.DummyMultiplexedNonBockingAdapter.send(
>> DummyMultiplexedNonBockingAdapter.java:72)
>>  ... 19 more
>> java.lang.NullPointerException
>>  at
>> pt.uc.dei.fincos.adapter.dummy.remote.DummyMultiplexedNonBockingAdapter.send(
>> DummyMultiplexedNonBockingAdapter.java:72)
>>
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