Make possible for ros2 topic hz to monitor the rates of multiple topics simultaneously as ros1 rostopic hz does.

[martinakos]

Feature request

Feature description

Make possible for ros2 topic hz to monitor the rates for of multiple topics simultaneously as ros1 rostopic hz does.

In ROS1 I can do:

rostopic hz /topic1 /topic2 /topic3

In ROS2 Humble I can only check the rate for one topic at a time:

ros2 topic hz /topic1

[fujitatomoya]

yeah, i think it is nice to have.

the following is output from rostopic hz from ROS 1 just a reference.

root@4b5f2b7e1de8:~# rostopic hz /chatter /rosout
subscribed to [/chatter]
subscribed to [/rosout]
 topic      rate   min_delta   max_delta    std_dev    window
=============================================================
/chatter   9.995   0.09971     0.1004      0.0001937   10
/rosout    9.996   0.09978     0.1004      0.0001766   10

 topic      rate   min_delta   max_delta    std_dev    window
=============================================================
/chatter   9.998   0.0997      0.1004      0.0001685   20
/rosout    9.998   0.09967     0.1004      0.0001661   20
....<snip>

[yaswanth1701]

Hi @fujitatomoya This feature sounds cool, If it's not implemented yet, I would like to give it a try. Can I ?

[fujitatomoya]

i think @iuhilnehc-ynos created https://github.com/ros2/ros2cli/pull/831 already. it would be nice if you can do review for that 👍

[yaswanth1701]

i think @iuhilnehc-ynos created #831 already. it would be nice if you can do review for that 👍

I haven't done a review before for PR but I will give it a try, thanks!

[felixdivo]

Just a side note: If once accepts new dependencies, it might make sense to not reinvent table printing here and use something proven. For example: rich or others.

[clalancette]

Just a side note: If once accepts new dependencies, it might make sense to not reinvent table printing here and use something proven. For example: rich or others.

We are careful with adding new dependencies. At the very least, the dependency needs to be available as a system package on Debian and Ubuntu (and preferably RHEL-9). Even then, we still have to deal with what happens on Windows. If we think the dependencies will make a significant difference, we can consider it, but someone needs to make the argument for it.

[felixdivo]

So, rich would be available on Ubuntu. I don't find it for Debian. Cons are the usual ones for new dependencies. Pros are

• Very simple UI creation, the code in this repo only does what it is responsible for: Collecting and structuring the HZ data. Displaying is done by a library that specializes on it
• It's still a command line tool and very portable and fairly minimalist
• Colors, highlights, ... make it easiert to maintain an overview
• Such a library might be useful in other places in this CLI tool as well

Similar pro arguments probably hold for other tools to. I like rich because it contains other nice CLI building blocks too, like pretty progress bars, for example. It is well maintained and from my experience very stable.