[failbuffer]

Could someone explain the joke? I've been dabbling with learning robotics and I've been confused by how ROS and ROS2 both appear to be actively developed/used. Is ROS2 a slow-moving successor version (like Python 3 was) or a complete fork?

[causal]

Slow-moving successor, which the community isn't exactly going wild over. It offers modest improvements in exchange for a painful upgrade process, and many of the original issues with ROS1 remaining unsolved.

The other half of the joke is that ROS was never an operating system either.

[moffkalast]

Well there is one thing that ROS 2 does better, you can declare params directly inside nodes and reconfigure them all without building extra config files. And it doesn't stop working if your local IP changes.

But the rest are firmly downgrades all around. It's slower (rclpy is catastrophically bad), more demanding (CPU usage is through the roof to do DDS packet conversions), less reliable (the RMWs are a mess), less compatible (armhf is kill). The QoS might count as an improvement for edge cases where you need UDP for point clouds, but what it mostly does on a day to day basis is create a shit ton of failure cases where there's QoS incompatibility between topics and things just refuse to connect. It's lot more hassle for no real gain.

[causal]

Config generally feels more complex though, since there isn't a central parameter server anymore. The colcon build system also just feels more complex now, which I thought was already impressively complex with catkin.

[moffkalast]

Yep it takes super long to get parameters from all nodes cause you need to query each one instead of the DDS caching it or something.

And yeah I forgot, there's the added annoying bit where you can't build custom messages/services with python packages, only ament_cmake can do it so you often need metapackages for no practical reason. And the whole deal with the default build mode being "copy all" so you need to rebuild every single time if you don't symlink, and even that often doesn't work. The defaults are all around impressively terrible, adding extra pitfalls in places where there were none in ROS 1.

[ModernMech]

It does a lot of things better but it also does a lot of things worse and also doesn't fix a lot of the real problems with ROS as a system.

[ModernMech]

ROS2 has been pushed a the successor to ROS for like a decade, and people still prefer ROS for various reasons. So yeah like Python 2/3 kinda.

[sashank_1509]

No it’s much worse, python3 was all round better, it just took a while to get all your dependencies ported which made the transition hard. Judging by the comments it doesn’t seem like people agree that ROS2 is even all round better from ROS.

[ModernMech]

It's funny this topic came up today because I have a group of students working on a ROS2 project and at our meeting this afternoon they had a laundry list of problems they've been having related to ROS2. I'm thinking our best option is to use ROS1...

You're right ROS2 isn't all round better than ROS so the transition will never happen fully.

FWIW I'm working on an actual replacement for ROS, I'll post it to ShowHN one day soonish :P