garbled data passed in cumulation buffer for decode(), probably when data re-transmission.

[Trustin Lee (이희승)]

Corruption due to JNI code?  I don't have much idea going on in my
head unfortunately.  I just wish you could write some reproduceable
code. :-(

— Trustin Lee, http://gleamynode.net/



On Sat, Sep 26, 2009 at 6:32 AM, huican ping <pinghuican at gmail.com> wrote:
> Hello Trustin,
>
> Thank you very much for your reply.
>
> Inside the getPipeline() method,
>                pipeline.addLast("timeout", new receiveTimeoutHandler);
>                pipeline.addLast("idle", new idleStateTimeoutHandler);
>                pipeline.addLast("decoder", new AcmeDecoder();
>                pipeline.addLast("encoder", new AcmeEncoder();
>
> 1:) Each time, when it is called, a new Decoder object will be create.
> I assume it should be thread-safe for that cumulation
> HeapChannelBuffer which is passed down from NioWorker. Am I right?
>
> 2:) further more, I noticed that even I set the Worker number to 1 at
> the time of start:
>                factory = new
> NioServerSocketChannelFactory(Executors.newCachedThreadPool(),
> Executors
>                                .newCachedThreadPool(), 1);
>     On our internal project, I still saw the corrupted data, for
> example, first 1024 bytes binary-zero, the remaining 42 byte are good.
> Or vise vesa.
>     I think for 1 Worker, there should only 1 WorkerThread, there
> should be no others to change the buffer, is it right?
>
>     Strange point:
>           I created a standalone project for decoder, used the same
> decoder/encoder and pipeline, and I never have any problem.
>
> 3:) Personaly, I think my Decoder should be fine. Then I used the
> DelimiterBasedFrameDecoder from your source, and in our complicated
> project, I also saw the bad data.
>
> 3:) Our internal project runs as a single java process, and it has
> lots of JNI calls though.
>
> Do you have any other insights?
>
> Thanks
> Ping
>
> On Fri, Sep 25, 2009 at 2:13 AM, Trustin Lee (이희승) <trustin at gmail.com> wrote:
>>
>> It will be a problem if messageReceived() is called by different
>> threads at the same time.  However, it does not happen because the
>> decoder is places before ExecutionHandler or ExecutionHandler uses
>> OrderedMemoryAwareThreadPoolExecutor.  If other executor is used and
>> the decoder is placed after the ExecutionHandler, FrameDecoder will
>> surely fail, but the failure should be very easy to reproduce.
>
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