abnormal exited rosnode still be seen on Master?

asked 2018-03-15 06:27:54 -0600

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Hello, everyone: I see Master is a xmlRPC server that maintains all the information of all nodes, but when a node abnormal exited, that node still can be seen on the master ? How can I check the active status of that node? Thanks!

answered 2018-03-15 07:13:10 -0600

gvdhoorn
86574 ●283 ●1432 ●1054 http://cor.tudelft.nl/

when a node abnormal exited, that node still can be seen on the master ?

yes.

rosnode cleanup is a way to try and rectify such a situation, but it's not entirely without faults. See the linked discussion in #q9521.

How can I check the active status of that node?

I would say the same way rosnode cleanup does it: rosnode_cleanup(). It essentially "pings" (xmlrpc) all nodes it knows about and any node that did not respond are considered dead, and deregistered.

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Btw: the various rosnode, rostopic and rosservice Python tools (and libraries) provide a lot of this functionality. Seeing your previous question (#q285515), I would first check those whenever you want to interact with the ROS node graph.