The only workaround I can think of right now is to do a thread switch. That is; A session which receives some data needs to post the data to a thread pool, and let that pool call write on the destination session.
It sounds a bit bad :( > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Sent: 30 October 2006 10:45 > To: mina-dev@directory.apache.org > Subject: Deadlock in Mina 1.0.0 > > Hi all, > > I'm having some problems with a deadlock in Mina 1.0.0. We are using > Java 5 on Windows XP, so I had to apply DIRMINA-277.patch. > > I have only created a snapshot (from Eclipse) of the two threads which > are involved in the deadlock (see below). It looks like both > threads are > blocked at: > > BaseIoSession.write: > > public WriteFuture write( Object message, SocketAddress > remoteAddress > ) > { > synchronized( this ) // <-- deadlock here > { > if( isClosing() || !isConnected() ) > { > return DefaultWriteFuture.newNotWrittenFuture( this ); > } > } > > WriteFuture future = new DefaultWriteFuture( this ); > write0( new WriteRequest( message, future, remoteAddress ) ); > > return future; > } > > > The thread snapshots shows that both treads already owns a lock and > wants a lock on another instance. > > (After a few moments of thinking) I think I know why the deadlock > occures. Mina is used by a routing instance, which have a front > connection and multiple backend connections. The class > DataStructureProtocolHandler in the trace below is an instance of > IoHandler. The trace shows that one IoHandler receives a message and > routs it to another IoHandler. So messageReceived is causing > a call to a > method on another IoHandler > (DatastructureProtocolHandler.consume). The > consume method is calling write on another IoSession. > > The deadlock occures when the front connection receives a > message and is > trying to sent it to a backend connection while that backend > connection > at the same time is trying to write a response back to the front > connection. > > How should I solve the problem? We have never had any problems with > prior versions of Mina and it happens very often with 1.0.0. > We have now > reverted back to a prior version. > > > Thanks for your time :) > Kaj > > > > -- Beginning of snapshot of the two threads > > Thread [AnonymousIoService-5] (Suspended) > owns: SocketSessionImpl (id=164) > waited by: Thread [SocketAcceptorIoProcessor-0.0] > (Running) > waited by: Thread [AnonymousIoService-16] (Suspended) > waited by: Thread [Timer-1] (Running) > waiting for: SocketSessionImpl (id=183) > owned by: Thread [AnonymousIoService-16] (Suspended) > SocketSessionImpl(BaseIoSession).write(Object, SocketAddress) > line: 137 > SocketSessionImpl(BaseIoSession).write(Object) line: 132 > DatastructureProtocolHandler.consume(ByteMessage, boolean) line: > 538 > DataConnector.consume(IDataSet, boolean) line: 109 > BackendHandler.consume(IDataSet, boolean) line: 65 > RoutingService.routeToBackend(RoutingInformation, String, > String, String, IDataSet) line: 458 > RoutingService.routeNewMessage(RoutingAlgorithm, String, String, > String, String, String, IDataSet) line: 406 > RoutingService.routeMessage(RoutingAlgorithm, String, > RoutingService$Request, IDataSet) line: 344 > RoutingService.onIncomingMessage(IDataSet) line: 193 > FrontendHandler.consume(IDataSet, boolean) line: 62 > DataConnector.consume(ByteMessage, boolean) line: 130 > DatastructureProtocolHandler.messageReceived(IoSession, Object) > line: 465 > AbstractIoFilterChain$2.messageReceived(IoFilter$NextFilter, > IoSession, Object) line: 189 > > SocketFilterChain(AbstractIoFilterChain).callNextMessageReceiv > ed(IoFilte > rChain$Entry, IoSession, Object) line: 502 > AbstractIoFilterChain.access$1000(AbstractIoFilterChain, > IoFilterChain$Entry, IoSession, Object) line: 52 > AbstractIoFilterChain$EntryImpl$1.messageReceived(IoSession, > Object) line: 777 > ExecutorFilter.processEvent(IoFilter$NextFilter, IoSession, > ExecutorFilter$EventType, Object) line: 243 > ExecutorFilter$ProcessEventsRunnable.run() line: 305 > ThreadPoolExecutor$Worker.runTask(Runnable) line: 650 > ThreadPoolExecutor$Worker.run() line: 675 > Thread.run() line: 595 > > > > Thread [AnonymousIoService-16] (Suspended) > owns: SocketSessionImpl (id=183) > waited by: Thread [AnonymousIoService-12] (Running) > waited by: Thread [AnonymousIoService-5] (Suspended) > owns: SocketSessionImpl (id=164) > waited by: Thread > [SocketAcceptorIoProcessor-0.0] (Running) > waited by: Thread > [AnonymousIoService-16] (Suspended) > waited by: Thread [Timer-1] (Running) > waited by: Thread [SocketAcceptorIoProcessor-1.0] > (Suspended) > waited by: Thread [Timer-2] (Running) > waiting for: SocketSessionImpl (id=164) > owned by: Thread [AnonymousIoService-5] (Suspended) > SocketSessionImpl(BaseIoSession).write(Object, SocketAddress) > line: 137 > SocketSessionImpl(BaseIoSession).write(Object) line: 132 > DatastructureProtocolHandler.consume(ByteMessage, boolean) line: > 538 > DataConnector.consume(IDataSet, boolean) line: 109 > FrontendHandler.consume(IDataSet, boolean) line: 64 > RoutingService.handleResponseMessage(String, IDataSet) line: 563 > > RoutingService.onBackendMessage(IDataSet) line: 532 > BackendHandler.consume(IDataSet, boolean) line: 61 > DataConnector.consume(ByteMessage, boolean) line: 130 > DatastructureProtocolHandler.messageReceived(IoSession, Object) > line: 465 > AbstractIoFilterChain$2.messageReceived(IoFilter$NextFilter, > IoSession, Object) line: 189 > > SocketFilterChain(AbstractIoFilterChain).callNextMessageReceiv > ed(IoFilte > rChain$Entry, IoSession, Object) line: 502 > AbstractIoFilterChain.access$1000(AbstractIoFilterChain, > IoFilterChain$Entry, IoSession, Object) line: 52 > AbstractIoFilterChain$EntryImpl$1.messageReceived(IoSession, > Object) line: 777 > ExecutorFilter.processEvent(IoFilter$NextFilter, IoSession, > ExecutorFilter$EventType, Object) line: 243 > ExecutorFilter$ProcessEventsRunnable.run() line: 305 > ThreadPoolExecutor$Worker.runTask(Runnable) line: 650 > ThreadPoolExecutor$Worker.run() line: 675 > Thread.run() line: 595 > > >
