exception when netconf try to write data on device

note: not occured everytime

from log:
2015-02-06 13:04:36,718 | WARN | c]-nio2-thread-5 | ncOutputStream$IoWriteFutureImpl | 148 - org.apache.sshd.core - 0.12.0 | Listener threw an exception
io.netty.util.IllegalReferenceCountException: refCnt: 0
at io.netty.buffer.AbstractByteBuf.ensureAccessible(AbstractByteBuf.java:1187)[130:io.netty.buffer:4.0.23.Final]
at io.netty.buffer.AbstractByteBuf.checkReadableBytes(AbstractByteBuf.java:1170)[130:io.netty.buffer:4.0.23.Final]
at io.netty.buffer.AbstractByteBuf.readBytes(AbstractByteBuf.java:676)[130:io.netty.buffer:4.0.23.Final]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter.toBuffer(AsyncSshHandlerWriter.java:162)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter.writeWithPendingDetection(AsyncSshHandlerWriter.java:77)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter.writePendingIfAny(AsyncSshHandlerWriter.java:130)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter.access$100(AsyncSshHandlerWriter.java:31)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter$1.operationComplete(AsyncSshHandlerWriter.java:99)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter$1.operationComplete(AsyncSshHandlerWriter.java:77)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.apache.sshd.common.future.DefaultSshFuture.notifyListener(DefaultSshFuture.java:261)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.future.DefaultSshFuture.addListener(DefaultSshFuture.java:212)[148:org.apache.sshd.core:0.12.0]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter.writeWithPendingDetection(AsyncSshHandlerWriter.java:77)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter.writePendingIfAny(AsyncSshHandlerWriter.java:130)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter.access$100(AsyncSshHandlerWriter.java:31)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter$1.operationComplete(AsyncSshHandlerWriter.java:99)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.AsyncSshHandlerWriter$1.operationComplete(AsyncSshHandlerWriter.java:77)[145:org.opendaylight.controller.netconf-netty-util:0.3.0.SNAPSHOT]
at org.apache.sshd.common.future.DefaultSshFuture.notifyListener(DefaultSshFuture.java:261)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.future.DefaultSshFuture.notifyListeners(DefaultSshFuture.java:247)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.future.DefaultSshFuture.setValue(DefaultSshFuture.java:175)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.channel.ChannelAsyncOutputStream.doWriteIfPossible(ChannelAsyncOutputStream.java:113)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.channel.ChannelAsyncOutputStream.onWindowExpanded(ChannelAsyncOutputStream.java:51)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.client.channel.AbstractClientChannel.handleWindowAdjust(AbstractClientChannel.java:329)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.session.AbstractConnectionService.channelWindowAdjust(AbstractConnectionService.java:224)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.session.AbstractConnectionService.process(AbstractConnectionService.java:151)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.session.AbstractSession.doHandleMessage(AbstractSession.java:399)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.session.AbstractSession.handleMessage(AbstractSession.java:295)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.client.session.ClientSessionImpl.handleMessage(ClientSessionImpl.java:256)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.session.AbstractSession.decode(AbstractSession.java:731)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.session.AbstractSession.messageReceived(AbstractSession.java:277)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.AbstractSessionIoHandler.messageReceived(AbstractSessionIoHandler.java:54)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.io.nio2.Nio2Session$1.onCompleted(Nio2Session.java:187)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.io.nio2.Nio2Session$1.onCompleted(Nio2Session.java:173)[148:org.apache.sshd.core:0.12.0]
at org.apache.sshd.common.io.nio2.Nio2CompletionHandler$1.run(Nio2CompletionHandler.java:32)
at java.security.AccessController.doPrivileged(Native Method)[:1.7.0_67]
at org.apache.sshd.common.io.nio2.Nio2CompletionHandler.completed(Nio2CompletionHandler.java:30)[148:org.apache.sshd.core:0.12.0]
at sun.nio.ch.Invoker.invokeUnchecked(Unknown Source)[:1.7.0_67]
at sun.nio.ch.Invoker$2.run(Unknown Source)[:1.7.0_67]
at sun.nio.ch.AsynchronousChannelGroupImpl$1.run(Unknown Source)[:1.7.0_67]
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)[:1.7.0_67]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)[:1.7.0_67]
at java.lang.Thread.run(Unknown Source)[:1.7.0_67]
2015-02-06 13:05:36,647 | WARN | tp1267059929-240 | WriteRunningTx | 169 - org.opendaylight.controller.sal-netconf-connector - 1.2.0.SNAPSHOT | {}: Failed to unlock running datastore
NetconfDocumentedException{message=RemoteDevice

: Unlocking running failed: Timeout waiting for task., errorType=application, errorTag=operation_failed, errorSeverity=warning, errorInfo={}}
at org.opendaylight.controller.sal.connect.netconf.sal.tx.AbstractWriteTx.invokeBlocking(AbstractWriteTx.java:61)
at org.opendaylight.controller.sal.connect.netconf.sal.tx.WriteRunningTx.unlock(WriteRunningTx.java:135)
at org.opendaylight.controller.sal.connect.netconf.sal.tx.WriteRunningTx.performCommit(WriteRunningTx.java:115)
at org.opendaylight.controller.sal.connect.netconf.sal.tx.AbstractWriteTx.commit(AbstractWriteTx.java:135)
at org.opendaylight.controller.sal.connect.netconf.sal.tx.WriteRunningTx.submit(WriteRunningTx.java:98)
at org.opendaylight.controller.sal.connect.netconf.sal.tx.ReadWriteTx.submit(ReadWriteTx.java:61)
at org.opendaylight.controller.sal.restconf.impl.BrokerFacade.putDataViaTransaction(BrokerFacade.java:228)[234:org.opendaylight.controller.sal-rest-connector:1.2.0.SNAPSHOT]
at org.opendaylight.controller.sal.restconf.impl.BrokerFacade.commitConfigurationDataPut(BrokerFacade.java:114)[234:org.opendaylight.controller.sal-rest-connector:1.2.0.SNAPSHOT]
at org.opendaylight.controller.sal.restconf.impl.RestconfImpl.updateConfigurationData(RestconfImpl.java:767)[234:org.opendaylight.controller.sal-rest-connector:1.2.0.SNAPSHOT]
at org.opendaylight.controller.sal.restconf.impl.StatisticsRestconfServiceWrapper.updateConfigurationData(StatisticsRestconfServiceWrapper.java:96)[234:org.opendaylight.controller.sal-rest-connector:1.2.0.SNAPSHOT]
at sun.reflect.GeneratedMethodAccessor49.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)[:1.7.0_67]
at java.lang.reflect.Method.invoke(Unknown Source)[:1.7.0_67]
at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:205)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:302)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.uri.rules.ResourceObjectRule.accept(ResourceObjectRule.java:100)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1511)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1442)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1391)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1381)[206:com.sun.jersey.jersey-server:1.17.0]
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:416)[204:com.sun.jersey.servlet:1.17.0]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:538)[204:com.sun.jersey.servlet:1.17.0]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:716)[204:com.sun.jersey.servlet:1.17.0]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:668)[175:org.apache.geronimo.specs.geronimo-servlet_3.0_spec:1.0]
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:684)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1496)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.servlets.CrossOriginFilter.handle(CrossOriginFilter.java:247)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.servlets.CrossOriginFilter.doFilter(CrossOriginFilter.java:210)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1467)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:499)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.ops4j.pax.web.service.jetty.internal.HttpServiceServletHandler.doHandle(HttpServiceServletHandler.java:69)[190:org.ops4j.pax.web.pax-web-jetty:3.1.0]
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:557)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:231)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1086)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.ops4j.pax.web.service.jetty.internal.HttpServiceContext.doHandle(HttpServiceContext.java:240)[190:org.ops4j.pax.web.pax-web-jetty:3.1.0]
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:428)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1020)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.ops4j.pax.web.service.jetty.internal.JettyServerHandlerCollection.handle(JettyServerHandlerCollection.java:77)[190:org.ops4j.pax.web.pax-web-jetty:3.1.0]
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.server.Server.handle(Server.java:370)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:494)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.server.AbstractHttpConnection.content(AbstractHttpConnection.java:982)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.content(AbstractHttpConnection.java:1043)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:865)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:240)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:667)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)[180:org.eclipse.jetty.aggregate.jetty-all-server:8.1.14.v20131031]
at java.lang.Thread.run(Unknown Source)[:1.7.0_67]
Caused by: java.util.concurrent.TimeoutException: Timeout waiting for task.
at com.google.common.util.concurrent.AbstractFuture$Sync.get(AbstractFuture.java:276)[75:com.google.guava:14.0.1]
at com.google.common.util.concurrent.AbstractFuture.get(AbstractFuture.java:96)[75:com.google.guava:14.0.1]
at org.opendaylight.controller.sal.connect.netconf.sal.tx.AbstractWriteTx.invokeBlocking(AbstractWriteTx.java:52)
... 58 more