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From "Emmanuel Lecharny (JIRA)" <j...@apache.org>
Subject [jira] Closed: (DIRMINA-684) NullPointerException when opening socket to localhost
Date Fri, 22 Jan 2010 17:37:21 GMT

     [ https://issues.apache.org/jira/browse/DIRMINA-684?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Emmanuel Lecharny closed DIRMINA-684.
-------------------------------------


> NullPointerException when opening socket to localhost
> -----------------------------------------------------
>
>                 Key: DIRMINA-684
>                 URL: https://issues.apache.org/jira/browse/DIRMINA-684
>             Project: MINA
>          Issue Type: Bug
>    Affects Versions: 2.0.0-M5
>         Environment: Linux
>            Reporter: David Rosenstrauch
>            Priority: Minor
>             Fix For: 2.0.0-RC2
>
>
> I have a MINA-based server I've written that's up and running and works fine.  I recently
added a new bit of functionality to it, however, and it's now throwing NullPointerExceptions
intermittently.
> The server uses a text-based protocol (using TextLineCodecFactory). I've added the capability
to give the server a command line parm which is the name of a text file, containing startup
commands that the server should execute after it starts up.  I'm doing this by having the
server open a java socket to the server's port on localhost, read the text file and write
(and flush) each command out to the socket.
> This is generally working, and the server is receiving and processing each command (not
always in the order sent, but I'm guessing that's an outgrowth of my using a thread pool,
and that's not a problem anyway). But from time to time, the server is spitting out this error:
> SEVERE: EXCEPTION :
> org.apache.mina.filter.codec.ProtocolEncoderException: java.lang.NullPointerException
>     at org.apache.mina.filter.codec.ProtocolCodecFilter.filterWrite(ProtocolCodecFilter.java:312)
>     at org.apache.mina.core.filterchain.DefaultIoFilterChain.callPreviousFilterWrite(DefaultIoFilterChain.java:506)
>     at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1400(DefaultIoFilterChain.java:48)
>     at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.filterWrite(DefaultIoFilterChain.java:814)
>     at org.apache.mina.core.filterchain.IoFilterEvent.fire(IoFilterEvent.java:65)
>     at org.apache.mina.core.session.IoEvent.run(IoEvent.java:64)
>     at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.runTask(OrderedThreadPoolExecutor.java:552)
>     at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.runTasks(OrderedThreadPoolExecutor.java:544)
>     at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.run(OrderedThreadPoolExecutor.java:488)
>     at java.lang.Thread.run(Thread.java:619)
> Caused by: java.lang.NullPointerException
>     at org.apache.mina.filter.codec.ProtocolCodecFilter.filterWrite(ProtocolCodecFilter.java:297)
>     ... 9 more
> Or sometimes another similar error as well:
> SEVERE: Error occurred during message handling
> org.apache.mina.filter.codec.ProtocolDecoderException: java.lang.NullPointerException
(Hexdump: 68 65 6C 70 0A 73 74 61 74 73 0A 71 75 65 72 79 20 31 32 33 34 0A)
>     at org.apache.mina.filter.codec.ProtocolCodecFilter.messageReceived(ProtocolCodecFilter.java:234)
>     at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:434)
>     at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:48)
>     at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.messageReceived(DefaultIoFilterChain.java:802)
>     at org.apache.mina.core.filterchain.IoFilterEvent.fire(IoFilterEvent.java:59)
>     at org.apache.mina.core.session.IoEvent.run(IoEvent.java:64)
>     at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.runTask(OrderedThreadPoolExecutor.java:552)
>     at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.runTasks(OrderedThreadPoolExecutor.java:544)
>     at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.run(OrderedThreadPoolExecutor.java:488)
>     at java.lang.Thread.run(Thread.java:619)
> Caused by: java.lang.NullPointerException
>     at org.apache.mina.filter.codec.ProtocolCodecFilter.messageReceived(ProtocolCodecFilter.java:224)
>     ... 9 more 
> Noteworthy aspects of my configuration:
> * using the M4 release of MINA
> * I'm not pausing between sending commands; i.e., I'm write and flushing them down the
socket as quickly as Java can send them
> * I'm using both a read and a write thread pool
> * building my filter chain as follows:
>     protocolAcceptor = new NioSocketAcceptor();
>     protocolAcceptor.setDefaultLocalAddress(new InetSocketAddress(protocolPort));
>     protocolAcceptor.setReuseAddress(true);
>     DefaultIoFilterChainBuilder filterChainBuilder = protocolAcceptor.getFilterChain();
>     filterChainBuilder.addLast("logger", new LoggingFilter(ProfileCacheServer.class));
>     readerThreadPool = new OrderedThreadPoolExecutor();
>     filterChainBuilder.addLast("readExecutor", new ExecutorFilter(readerThreadPool, IoEventType.MESSAGE_RECEIVED));
>     filterChainBuilder.addLast("codec", new ProtocolCodecFilter(new TextLineCodecFactory(ParseConstants.UTF8_CHARSET)));
>     writerThreadPool = new OrderedThreadPoolExecutor();
>     filterChainBuilder.addLast("writeExecutor", new ExecutorFilter(writerThreadPool,
IoEventType.WRITE));
>     protocolAcceptor.setHandler(protocolHandler); 
> I actually did find a way to "fix" this problem but someone on the mailing list suggested
that MINA shouldn't be throwing NPE's regardless.  Fix is as follows:   I was originally just
dropping the connection on the client side when I was finished.  But after changing my code
to issue a proper "close connection" command to the server before disconnecting, it looks
like the NPE's go away. 

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