How to restart a Task.supervisor

Phoenix Forum Questions / Help
,
1

Hello,

Having a Task.supervisor under a phoenix app, and using it with Task.supervisor.async_no_link

is there a way to stop the stream from running and restart the supervisor thus killing all tasks (current and coming next from the stream)?

you can get the currently running tasks with SupName.children() but since this is a stream, the children tasks are always moving. How to stop the stream, kill all and reset the supervisor to wait for other tasks ?

thanks

2

If you have named your supervisor (see here Task.Supervisor — Elixir v1.12.2), you can use Process — Elixir v1.12.2 to kill that process using its name.
Since it’s already under a supervisor, it will be restarted.

Or if you just want to kill all children, use Task.Supervisor — Elixir v1.12.2 and kill all children, without restarting supervisor.

3

I have finally found Supervisor.stop( name_of_supervisor)

how would you do it with Process ?
kill all children is not possible since it is a stream

4

What do you mean by it’s a stream? What kind of stream? Is it infinite? Does it have some kind of pause/stop?

Streams are a wide topic, by just saying it’s a stream it can mean different things. Finite lists are also kind of streams.

5

using Task.Supervisor.async_stream_nolink which processes a list of tasks submitted in a streamed way for instance 6 by 6

6

Can you call Supervisor.stop on it?

In general, what are you trying to achieve? What kind of stream of data are you processing? Maybe there’s a different abstraction or package that would fit the job better?

1 Like
7

list of tasks submitted in a streamed way for instance 6 by 6

How do you do this? Where do you get this stream from? Do you use Stream module to create a stream, then pass it to Task.Supervisor.async_stream_nolink?

What I’ve said was about the stream you give to the Task.Supervisor.async_stream_nolink, not the one it returns.

8

biglist is a list of records
EmailTaskSupervisor is the name of the Task.Supervisor, children of application
Sender and send_email are the module and the function inside called on each element of biglist

stream = Task.Supervisor.async_stream_nolink(
EmailTaskSupervisor,
biglist,
Sender,
:send_email,

)

to start the stream of tasks and be able to continue normal process

Task.start(fn -> Enum.to_list(stream) end)
9

Supervisor.stop is what I did finally, to restart, I resubmit a stream of remaining tasks that were not executed when I stopped the supervisor