Can mix tasks be gracefully shutdown?

Questions / Help
,
1

Is there any way to handle task termination gracefully?

When i do ctrl-c no form for shutdown hook is called in the task. I have yet to see an example or google search hit for something that shows how this can be solved.

Is it a futile project and a dead end? Will mix tasks always be hard killed with no way to gracefully shutdown?

2

I started using Ctrl + \ a while back and I think it is more graceful than Ctrl + c.

2 Likes
3

Might be, but im more interested in figuring out how to gracefully terminate a mix task from inside the task. But alas there does not seem to be passed events to the task from mix task execution system.

4

Maybe calling System.halt(0)

1 Like
5

Maybe, but it should be called when the task is being terminated from the outside. With Ctrl-c.

6

Well, Ctrl-C sends a SIGINT signal to the process. You should be able to do what you want using the signal handling capabilities of the kernel, more specifically erl_signal_server.

1 Like
7

I use System.stop() sometimes if I want to try graceful exit. But, I don’t think there is any issue doing Ctrl-c twice. Is there any specific reason for you to ask this?

1 Like
8

its about a task in testcontainers for elixir, that spawns a database container, which can be reusable. When forcefully terminated, my thought was to stop the database container causing the spawned tests via System.cmd to fail and complete faster.

But as this thread has developed, there is no way to listen for an sigint interrupt in the task, which is sad because its a core feature that should be there.

But anyway, its no big deal really. I will just need to add a disclaimer that if the task is forcefully killed and if the container is reused, the tests will continue running happily until completed in the background and then die off. Which is not a big deal, unless you rerun the task which causes the same container to be reused and tables will be recreated, and might fail if the old test process is using the tables. slight annoyance maybe

:man_shrugging:

9

however not to brag or anything but mix testcontainers.test --watch lib --watch test is pretty nice to work with with reusable database container. Just saying. Just wish i could cancel it. But now when i think about it, why should i need to cancel it? tests running for a long time and wont stop? hanging ? then it doesnt matter? maybe this is a figurative problem, a problem that doesnt exist? yes … i think so