Supervisor web ui can only handle a limited number of entries depending on the length of the program name

[awesomebytes]

I've been adding entries to my supervisor server (thanks for the project!) but somehow I found an arbitrary limit on the number of entries that can be shown in the web ui.

The moment I have 54+ entries, the 54th entry half appears and the following don't appear. Furthemore, the site gets stuck in an always loading state.

Screenshot of it happening:

I made a couple of examples where this happens and I discovered it is related with the length of the text displayed.

How to reproduce:
Clone the repository where I prepared a couple of example .conf files:

git clone https://github.com/awesomebytes/supervisor_web_ui_bug

Run one of the example files and access the web ui.

cd supervisor_web_ui_bug
supervisord -n -c supervisor_60.conf
# Access http://127.0.0.1:9001

• Version of supervisor: 4.2.1
• OS: Ubuntu 18.04
• Browsers: Chromium 84.0.4147.105, Firefox 79.0 (and a bunch of other versions on other machines)

[awesomebytes]

Update: I just tried using supervisor from Python3 instead of Python2.7 and the bug doesn't exist that way.

[bbg221]

this bug is still in with python2.7, could someone fix it?

[awesomebytes]

@bbg221 I'm not the maintainer, however, I doubt it will be fixed given running supervisor with Python 3.X works and support for Python2.7 is mostly dropped everywhere.

[mnaberez]

#1493 (comment)

If there are too many processes to monitor, the page cannot be fully displayed. I find it caused by this line of code：

supervisor/supervisor/medusa/producers.py

Line 88 in d76f548

out_buffer_size = 1<<16

I temporary fix it by change 1<<16 to 1<<17. just don't know if I'm doing it right