MongooseIM (and ejabberd) are too big and complex to allow full hot code reloading. Moreover this feature is quite rarely used in any Erlang software.

I'm not sure how you've measured how often hot code reloading is used? I use it for almost all of my production pushes.

However, I agree that it's generally hard to use it for third party software; upgrades would either become cumbersome because you have to follow the same piecewise upgrade process the developer followed, or the developer would have to do a lot of extra work to ensure upgrades between releases were solid; the recent addition of atomic loading of multiple modules would probably help.

I could point to this: https://stackoverflow.com/questions/31080970/erlang-hot-code...