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From "Torsten Curdt" <tcu...@apache.org>
Subject Re: [Javaflow] A NullPointerException
Date Thu, 13 Nov 2008 04:29:03 GMT
Did you try to debug to see what actually becomes null?
You don't serialize the continuations - do you?

cheers
--
Torsten

On Wed, Nov 12, 2008 at 7:17 AM, Avinash Lakshman
<avinash.lakshman@gmail.com> wrote:
> I have a continuation based setup where I am trying to do asynchronous I/O.
> I submit a read request and then suspend() the continuation. Later a
> callback is invoked on read completion and the continuation is resumed.
> However when I resume the continuation I get a NullPointerException stack
> trace shown below:
>
> Exception in thread "DISK-IO-POOL:1" java.lang.NullPointerException
>      at java.nio.ByteBuffer.wrap(ByteBuffer.java:392)
>      at
> com.facebook.infrastructure.io.AIORandomAccessFile.doWrite(AIORandomAccessFile.java:400)
>      at
> com.facebook.infrastructure.io.AIORandomAccessFile.flushBuffer(AIORandomAccessFile.java:368)
>      at
> com.facebook.infrastructure.io.AIORandomAccessFile.seek(AIORandomAccessFile.java:509)
>      at
> com.facebook.infrastructure.io.AIORandomAccessFile.read(AIORandomAccessFile.java:562)
>      at java.io.RandomAccessFile.readInt(RandomAccessFile.java:771)
>      at
> com.facebook.infrastructure.io.ReadImpl.run(AIORandomAccessFile.java:727)
>      at
> org.apache.commons.javaflow.bytecode.StackRecorder.execute(StackRecorder.java:94)
>      at
> org.apache.commons.javaflow.Continuation.execute(Continuation.java:172)
>      at
> org.apache.commons.javaflow.Continuation.continueWith(Continuation.java:168)
>      at
> com.facebook.infrastructure.io.AIORandomAccessFile$ReadCompletionHandler.completed(AIORandomAccessFile.java:132)
>      at
> com.facebook.infrastructure.io.AIORandomAccessFile$ReadCompletionHandler.completed(AIORandomAccessFile.java:114)
>      at sun.nio.ch.Invoker.invokeDirect(Invoker.java:114)
>      at
> sun.nio.ch.SimpleAsynchronousFileChannelImpl$3.run(SimpleAsynchronousFileChannelImpl.java:363)
>      at
> org.apache.commons.javaflow.bytecode.StackRecorder.execute(StackRecorder.java:94)
>      at
> org.apache.commons.javaflow.Continuation.execute(Continuation.java:172)
>      at
> org.apache.commons.javaflow.Continuation.continueWith(Continuation.java:168)
>      at
> com.facebook.infrastructure.concurrent.ContinuationsExecutor.runWorker(ContinuationsExecutor.java:1193)
>      at
> com.facebook.infrastructure.concurrent.ContinuationsExecutor$Worker.run(ContinuationsExecutor.java:608)
>      at java.lang.Thread.run(Thread.java:713)
>
> Here is the call stack before the suspend():
>
> java.lang.Thread.run/
> com.facebook.infrastructure.concurrent.ContinuationsExecutor$Worker.run/
> com.facebook.infrastructure.concurrent.ContinuationsExecutor.runWorker/
> org.apache.commons.javaflow.Continuation.continueWith/
> org.apache.commons.javaflow.Continuation.execute/
> org.apache.commons.javaflow.bytecode.StackRecorder.execute/
> com.facebook.infrastructure.io.ReadImpl.run/
> java.io.RandomAccessFile.readInt/
> com.facebook.infrastructure.io.AIORandomAccessFile.read/
> com.facebook.infrastructure.io.AIORandomAccessFile.seek/
> com.facebook.infrastructure.io.AIORandomAccessFile.fillBuffer2
>
> Could someone please advice as to what might be going on over here?
>
> Thanks
> A
>

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