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1

Running a node on multiple CPU cores

asked 2018-05-16 09:26:33 -0500

eirikaso
108 ●12 ●16 ●21

Hi I am trying to publish a camera stream using the "uvc_camera" ( http://wiki.ros.org/uvc_camera ) package. All works well, but I get a low framerate on high resolution. This seems to be due to cpu overload. When I check the cpu usage with "htop", only one core seems to be used by ROS and all the capacity is used. On the other cores however, only avout 20% capacity is used.

Is there any way to make ROS run this node using multiple cpu cores?

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answered 2018-05-16 09:28:28 -0500

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

updated 2018-05-16 09:43:46 -0500

No. Not unless the node itself already uses/supports multithreading.

Note that this is not a ROS limitation, but a basic OS/process scheduling constraint: there is no way to split workloads in the way you ask for by the OS if the program has not been created with multi-core support already.

Edit: something to check: if you built the pkg from source, be sure to build with optimisations enabled. Use a CMake build type that turns those on (ie: Release or RelWithDebInfo). Packages released through and installed from the ROS buildfarm already come with optimisations.

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Interesting! Could you share a link to learn how to write such code? Or perhaps keywords I should search to find such resources? Thanks

parzival ( 2021-04-10 02:26:45 -0500 )edit

Could you share a link to learn how to write such code?

what sort of code?

gvdhoorn ( 2021-04-10 04:42:48 -0500 )edit

multithreading/multiprocessing

parzival ( 2021-04-10 05:20:44 -0500 )edit

That wouldn't really be ROS specific. Standard multi-threading can be used.

In ROS 1, one thing to keep in mind is that using a MultiThreaded or Async spinner will not automatically make callback processing multithreaded.

gvdhoorn ( 2021-04-10 05:28:51 -0500 )edit

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Asked: 2018-05-16 09:26:33 -0500

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Last updated: May 16 '18

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