Exception when shutting down nodes

[jubeira]

When the shutdown() method of NodeMainExecutor is called, an exception is thrown (only) if any of the running nodes is connected to a topic that has subscribers:

May 24, 2017 6:01:09 PM org.ros.internal.node.client.Registrar onPublisherRemoved
INFO: Unregistering publisher: Publisher<PublisherDefinition<PublisherIdentifier<NodeIdentifier</joint_publisher, http://10.34.0.70:42274/>, TopicIdentifier</rosout>>, Topic<TopicIdentifier</rosout>, TopicDescription<rosgraph_msgs/Log, acffd30cd6b6de30f120938c17c593fb>>>>
May 24, 2017 6:01:09 PM org.jboss.netty.channel.DefaultChannelPipeline
WARNING: An exception was thrown by a user handler while handling an exception event ([id: 0x05fce1f1, /10.34.0.70:54329 :> /10.34.0.70:37488] EXCEPTION: java.lang.IllegalStateException: No publisher for topic: /talker)
org.ros.exception.RosRuntimeException: java.lang.IllegalStateException: No publisher for topic: /talker
	at org.ros.internal.transport.ConnectionTrackingHandler.exceptionCaught(ConnectionTrackingHandler.java:81)
	at org.jboss.netty.channel.Channels.fireExceptionCaught(Channels.java:533)
	at org.jboss.netty.channel.AbstractChannelSink.exceptionCaught(AbstractChannelSink.java:49)
	at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:296)
	at org.jboss.netty.handler.codec.frame.FrameDecoder.unfoldAndFireMessageReceived(FrameDecoder.java:458)
	at org.jboss.netty.handler.codec.frame.FrameDecoder.callDecode(FrameDecoder.java:439)
	at org.jboss.netty.handler.codec.frame.FrameDecoder.messageReceived(FrameDecoder.java:311)
	at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:268)
	at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:255)
	at org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:91)
	at org.jboss.netty.channel.socket.nio.AbstractNioWorker.processSelectedKeys(AbstractNioWorker.java:373)
	at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:247)
	at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:35)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.IllegalStateException: No publisher for topic: /ur_plugin/joint_states
	at com.google.common.base.Preconditions.checkState(Preconditions.java:149)
	at org.ros.internal.transport.tcp.TcpServerHandshakeHandler.handleSubscriberHandshake(TcpServerHandshakeHandler.java:94)
	at org.ros.internal.transport.tcp.TcpServerHandshakeHandler.messageReceived(TcpServerHandshakeHandler.java:67)
	... 13 more

It looks like some TCP connection handler is still active and shutting down the node leaves something in an illegal state.
The line throwing the exception is this one:
https://github.com/rosjava/rosjava_core/blob/kinetic/rosjava/src/main/java/org/ros/internal/transport/tcp/TcpServerHandshakeHandler.java#L94

[jubeira]

This is happening after calling the shutdown method of a node, which shuts down the TopicParticipantManager (see https://github.com/rosjava/rosjava_core/blob/kinetic/rosjava/src/main/java/org/ros/internal/node/DefaultNode.java#L408).
Perhaps there is some callback for the TCP connection in the HandshakeHandler named above that has to be unregistered at that step so that it is no longer called.

@stratomda maybe you've seen this? I think the fix in #238 is correct, and perhaps something else needs to be done there to cleanup the active connections...

[jubeira]

Update: the same issue arises when the shutdown method for a Publisher is called if the topic has subscribers (that's why it happens when a node is shut down). Apparently something else has to be done when a publisher is shut down.