Logs are lost upon hitting enter when running iex -S mix

Questions / Help
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1

Hi,

I recently upgraded to Elixir 1.15.5 and I’m observing annoying behavior: when I start my application with iex -S mix logs output by the application disappear when I hit enter in the console.

Here’s a video showing the issue:

My system:
Elixir: 1.15.5
Erlang: 26.0
OS: MacOS 13.5.2
Shell: zsh 5.9

P.S: I tried with another mix application and I get the same behavior.

Perhaps someone knows what’s going on here, or has some tips.

Thanks!

2

Yes, it looks like logs “disappear” at some point. But also on your video, logs appear to be there if you scroll up a bit, aren’t they?

3

I think this issue is related to terminal, I used to have constant console warping issues on AWS EC2 instances, no idea what it was about.

4

Only the ones produced before I start interacting with the terminal.
The logs generated after I enter a command disappear completely when I enter a second command

EDIT: actually, this is incorrect. Whenever I enter a command the screen is cleared and the log messages that were outside of the screen can be recovered by scrolling up, but the messages that were visible are wiped forever

5

Sure, it must be related to the terminal. But the issue is not there when I switch to Elixir 1.14.

I wonder what changed between 1.14 and 1.15 that could cause something like this? I’ll investigate a bit more when I find some time.

1 Like
6

If anyone experiences the same issue: the problem disappears if you use Elixir 1.15.5 with Erlang 26.0.2 instead of 26.

I’m quite baffled, and I quickly searched the Erlang/OTP changelog for a possible explanation, but didn’t find any.

1 Like
7

I think it is the same bug as described in ticket OTP-18652 aka PR-7242.

2 Likes
8

I think it is the same bug as described in ticket OTP-18652 aka PR-7242.

Awesome! Thank you so much for the pointer. I was starting to believe that I was imagining things :laughing: