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In which order are callback functions in a node which offers a service and also subscribes to a topic?

asked 2019-02-24 18:13:10 -0500

eric.valls.grunewald gravatar image

I want to use a node that both offers a service and subscribes to a topic. If, when ros::spin() is called I have both a new message in the topic and a request from the service, which callback function is called first? The service or the subscriber one?

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answered 2019-02-24 19:23:43 -0500

updated 2019-03-01 17:49:48 -0500

I'd recommend reading the Callbacks and Spinning page page. Since it sounds like you are calling ros::spin(), then all callbacks get put into a callback queue in the order in which they are received. Then every call to ros::spin() will handle the callback at the front of the queue. So the answer to your question depends on the order in which the service request and the topic were received.

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Asked: 2019-02-24 18:13:10 -0500

Seen: 393 times

Last updated: Mar 01 '19