Hello, I have yet to find a solution to this problem, additionally I have yet to replicate it artificially. I am wondering if anyone has come across it.

I have a program that is built upon a ROS network, there are times when publishers are frozen or taken offline, and then unfrozen and respawned. There are times after this when the subscriber does not receive any messages, it simply does nothing until it is shut down and restarted, when it will start receiving messages again. Has anyone come across this before?

I have tried to induce this artificially by manually shutting down and restarting a publisher but the subscriber always reconnects to the topic.

Some information that may be useful, we are currently running ROS Hydro on a custom WinROS build. The deployed system is spilt across two computers.

ROS_IP is set

ROSMASTERURI is set

ROSLaunch is not being used, so bringing down the first node does not bring down ROSCore (https://answers.ros.org/question/10171/ros-msgs-not-received-if-publisher-starts-after-subscriber/)

Is there a way to explicitly tell the ROS Master to send another callback to nodes that are subscribed to a topic informing them that there is a new publisher?

EDIT:

I finally produced the error and roswtf can detect it with: "the following nodes should be connected but aren't"

I have continued digging and still have no solution, though I have found more information that may help, the ROS Master logs list the following errors, which leads to to the following open issue - https://github.com/ros/ros_comm/issues/572

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[rosmaster.master][INFO] 2018-04-04 15:51:15,819: publisherUpdate[/node2] -> http://192.168.0.134:55036/ [rosmaster.threadpool][ERROR] 2018-04-04 15:51:16,823: Traceback (most recent call last):

File "C:\opt\ros\hydro\x64\lib\site-packages\rosmaster\threadpool.py", line 218, in run result = cmd(*args)

File "C:\opt\ros\hydro\x64\lib\site-packages\rosmaster\masterapi.py", line 189, in publisherupdatetask xmlrpcapi(api).publisherUpdate('/master', topic, puburis)

File "C:\Python27\lib\xmlrpclib.py", line 1224, in call return self.send(self.name, args)

File "C:\Python27\lib\xmlrpclib.py", line 1578, in request verbose=self.verbose

File "C:\Python27\lib\xmlrpclib.py", line 1264, in request return self.singlerequest(host, handler, requestbody, verbose)

File "C:\Python27\lib\xmlrpclib.py", line 1292, in singlerequest self.sendcontent(h, request_body)

File "C:\Python27\lib\xmlrpclib.py", line 1439, in sendcontent connection.endheaders(requestbody)

File "C:\Python27\lib\httplib.py", line 991, in endheaders self.sendoutput(message_body)

File "C:\Python27\lib\httplib.py", line 844, in sendoutput self.send(msg)

File "C:\Python27\lib\httplib.py", line 806, in send self.connect()

File "C:\Python27\lib\httplib.py", line 787, in connect self.timeout, self.source_address)

File "C:\Python27\lib\socket.py", line 571, in create_connection raise err

error: [Errno 10061] No connection could be made because the target machine actively refused it

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[rosmaster.master][INFO] 2018-04-04 16:03:50,592: publisherUpdate[/node] -> http://192.168.0.134:55698/ [rosmaster.threadpool][ERROR] 2018-04-04 16:03:50,592: Traceback (most recent call last):

File "C:\opt\ros\hydro\x64\lib\site-packages\rosmaster\threadpool.py", line 218, in run result = cmd(*args)

File "C:\opt\ros\hydro\x64\lib\site-packages\rosmaster\masterapi.py", line 189, in publisherupdatetask xmlrpcapi(api).publisherUpdate('/master', topic, puburis)

File "C:\Python27\lib\xmlrpclib.py", line 1224, in call return self.send(self.name, args)

File "C:\Python27\lib\xmlrpclib.py", line 1578, in request verbose=self.verbose

File "C:\Python27\lib\xmlrpclib.py", line 1264, in request return self.singlerequest(host, handler, requestbody, verbose)

File "C:\Python27\lib\xmlrpclib.py", line 1297, in singlerequest return self.parseresponse(response)

File "C:\Python27\lib\xmlrpclib.py", line 1473, in parse_response return u.close()

File "C:\Python27\lib\xmlrpclib.py", line 793, in close raise Fault(**self._stack[0])

Fault: