Very slow to load?

This is my first week teaching with TheConstructSim. Many times, it loads quite quickly. However, at my 7am MST class, 2 of the last 3 days, it has loaded very slowly. I start the ROS in 5 Days class and it takes >3 minutes to see the content, simulator, and command line. The IDE takes around 5 minutes to load. This happens on both my mac and windows machines in chrome and edge.
Any ideas?

My afternoon class (~2:30pm MST) has not seen this problem.


Oh, maybe it’s the difference between using ROS in 5 Days with kinetic vs. noetic?

Nope - that wasn’t the difference. It seemed like things were very slow for multiple students, but that the kinetic version of ROS in 5 Days did eventually load.

Hi Matt,

I’m sorry that you are having this issue. Thank you for letting us know about it.

I’m doing some investigations and need to get all the facts right. This is what I’m able to gather from what you have posted so far; please let me know if it’s correct:

  • This problem only happens in your morning class, around 07:00 MST. That would be around 15:00 CST. It doesn’t happen in the afternoon class, around 14:30 MST, which would be around 22:30 CET.
  • In the first day of your class, which should be Tuesday January 12, 2021, you did not see this issue at all.
  • You used the Edge browser at some point. Please only use Chrome and Firefox; these are the browsers we support at this time.
  • The Kinetic version of ROS Basics in 5 Day did eventually load…this suggests that the Noetic version did not load at all (vs slow loading) for some. Not clear about this, could you confirm? And also please let us know if you are loading the Kinetic or Noetic or both versions now.

Thanks in advance for clarifying the above points and telling us anything else that might help us find the root cause of this problem.


We had trouble at 7am MST on Tuesday the 12th. Wed the 13th it was OK, but then the trouble came back today. We did not see the same trouble during the afternoon.
We’re now sticking with chrome and firefox.
This morning, we were able to get ROS Basics in 5 Days to work after 3-5 minutes. ROS Noetic either didn’t load, or the first commands didn’t work (and threw a bunch of errors making it look like there was python 2 commands instead of python 3).

If I open up ROS Basic in 5 days for python / kinetic, what is the expect load time for everything? I’m sure it’s machine and connection dependent, but it makes me nervous when it take ~30 seconds some days/times and ~5 minutes at other day/times (on the same computer with the same internet connection).

Hi Matt,

Thank you for providing more context.

It depends. If you’re working during off-peak hours, it’s around 30-60 seconds. If during peak hours, it might take 3-5 minutes depending on how many users are accessing the courses at the same time.

Your morning session coincides with our peak period (~15:00 CET) while your afternoon sessions happen in the off-peak period (~22:30 CET). This explains why the courses load faster in the afternoon sessions. We are working on improving the loading time during peak periods.

As for the Noetic course issues, could you please ask students who experience specific errors to send us details of these errors including screenshots where possible? We are migrating fully to Noetic this week and we will disable the Kinetic courses, so we would like to solve all errors related to Noetic.

Oh, weird. I had assumed you were using something like AWS and automatically scaling to the load present. I’ll tell the students to start up the simulator as soon as class starts, rather than waiting for when they need it.

We are migrating fully to Noetic this week and we will disable the Kinetic courses, so we would like to solve all errors related to Noetic.

I’ll get back to you on the errors we were experiencing. But hopefully you don’t actually mean you’ll disable the Kinetic courses? Our students started the ROS in 5 days last week, are finishing it this week, and will be demoing their results the following week. Disabling courses during the term would be incredibly disruptive and I really hope that’s not going to happen?


Yes, there’s automatic scaling, but the new instances created during scaling need some time to boot up and set up the environment. The instances used during off-peak are mostly “standby” - already booted and set up.

Thank you for your understanding and for proposing a thoughtful workaround!

Thank you.

We intend to disable the Kinetic courses, but I’ll pass your concerns to the migrations team. We’ll keep you in mind as we migrate.


Thanks for passing along my concerns. Maybe they could make a compromise by not letting students start new Kinetic courses, but let them continue to work on, and demonstrate, courses that have already begun?

Hi Matt,

The migration team informed me they have to migrate everything tonight and disable the Kinetic courses, in order to make the transition as smooth as possible for the users. Only that that means users will need to work with the Noetic courses after that.

That said, we are doing everything possible to ensure that the Noetic courses work and we’ll be on the lookout for any problems that may arise. On this note, could you please send me the issues you have with the Noetic course ASAP?

Finally, what are the end times for your morning and afternoon classes? I understand they start at 15:00 CET and 22:30 CET…but when do they end? By the time you start the afternoon class today, we may already have done the transition, and you may have to work with the Noetic courses, but we don’t want to do the migration while you are having a class.


Our classes are (all mst)
T/Th, 7am-8:20am, 3:30-4:50pm
W, 7am-9:50, 2pm-4:50

As long as they can jump to the part of the ROS in 5 days Noetic course that they were doing in Kinetic, I guess this will be OK, just a bit jarring for the students.

Here’s what I get when I try to load ROS in 5 Days with Noetic in Chrome Version 87.0.4280.141 (Official Build) (x86_64) on Mac OS 11.1:

Thanks again,

Hi ,

We just made a deploy of a fix for that issue. Could you close the course in the main dashboard and when its closed. Then open a new course? Roslaunch should work now

Unfortunately, I’ve been waiting for >10 minutes and get this:

Scratch that - it just loaded successfully after ~12 minutes.
But now I’m back to getting the error that looks like the wrong version of Python:

Hi Matt,

Thank you for sharing your class schedule with us and for telling us about the issues you are having with Noetic.

Your schedule has been noted and we are keeping that in mind for the migration. Also, we are working on the issues:

  • Improving the loading time of some simulations, like the one you shared.
  • Fixings issues with Python 2 statements in some of the packages.

As for “jump to the part of the ROS in 5 days Noetic course that they were doing in Kinetic”, I think you mean if they will automatically get taken to the same unit they were working on in Kinetic? They might have to manually navigate to the unit they were working on the first time the course is opened, but thereafter they will be taken to where they left off.

We have deployed the fix for that issue of bb8 teleop :wink:

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2 posts were split to a new topic: The simulation and shells of unit 7 ROS in 5 Days are stuck in loading

We reinstated the old versions with Kinetic until we are sure everything works 100%

Hi Bayodesegun,

That’s right - as long as my students can jump forward to the same point in the Noetic course, without having to recreate files made earlier in the class, things will be fine.

I’m glad that Kinetic is still being supported until Noetic works 100%. I was getting pretty worried when the very first statement in the very first course (ROS in 5 Days) did not execute. I understand that I could update the notebook myself to use python 3 instead of python 2, but I really expected the courses provided to work “out of the box” without having to debug things. I expect my students to spend a bunch of time debugging their own code, but not having to debug the provided examples. Making sure all the courses completely work before switching to the new system seems like a really important quality check.

I completely understand that you all want to upgrade to the latest version of ROS. But I would like to stress again that disabling the Kinetic during the semester is a bit risky. I’m glad that you’re all committee to getting everything working smoothly and helping us succeed during an already challenging remote semester!

Thanks again,

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