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Roscore force unregister of node that died

asked 2018-09-18 13:23:58 -0600

Hi!

I believe I'm running into a situation in a multi machine setup.

Setup

  1. Machine running rosmaster
  2. Second machine that's properly setup to recognize the machine running roscore

What I believe I'm observing sometimes is that if I forcibly kill the second machine (for example, disconnect the power), since the ros::shutdown() is not called the roscore still thinks that the node is there and lists it.

Is there any way I can force roscore to kill the topic that is connected to the node that doesn't exist anymore?

Since I'm using anonymous node names (and I have to do it in my case) is that if I forcibly reset my slave computer I will end up with a rosnode list showing two topics, one of which is not connected to anything.

Any tips how to handle it neatly would be highly appreciated!

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Comments

rosmaster doesn't have any timeout for nodes if they crash, so it will keep remembering them until a new node starts with the same name. I'm pretty sure this isn't a new issue, but I can't find a bug report for it.

ahendrix gravatar imageahendrix ( 2018-09-18 14:16:52 -0600 )edit

Related Q&As: #q9521 and #q285530.

gvdhoorn gravatar imagegvdhoorn ( 2018-09-18 15:23:07 -0600 )edit

rosnode cleanup should do the trick.

Choco93 gravatar imageChoco93 ( 2018-09-19 01:21:37 -0600 )edit

Thanks for the helpful comments! I figured a better approach than force unregistering the node. Instead in my case it's sufficient to use node_alive and keep track of alive nodes

msadowski gravatar imagemsadowski ( 2018-10-04 02:27:20 -0600 )edit

Wondering how this compares to bond (at least in C++).

gvdhoorn gravatar imagegvdhoorn ( 2018-10-04 02:31:37 -0600 )edit

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answered 2018-10-04 02:37:16 -0600

After thinking about it for some time and doing some experiments I decided unregistering a node is a bad idea in my case (it seems you can create quite a lot of trouble if a node is not available because for example the network is down for a second).

What I found to be a great alternative without a brute force approach is node_alive package that allows me to keep track of nodes that are see as alive. Then I can use this information to keep track of 'pingable' nodes and use them accordingly in my setup.

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Asked: 2018-09-18 13:23:58 -0600

Seen: 161 times

Last updated: Oct 04 '18