SIGUSR1

[franklinvp]

I would like to define a custom handle_sigusr1 such that upon sending SIGUSR1 to a worker it runs a function to update certain internal data.

How to do this?

Currently it looks like when doing kill -SIGUSR1 <worker PID>, the worker dies and a new one gets created.

---

By reading the implementation, it looks like I can do

import uvicorn

def handle_usr1(*args):
    ... # update stuff

setattr(
    uvicorn.supervisors.multiprocess.Multiprocess,
    'handle_usr1',
    handle_usr1
)

Now, I would like to do the updating as a background task. I still need to figure out how to do this.

[franklinvp]

OK. I think I figured it out.

1. Add a method handle_usr1 to uvicorn.supervisors.multiprocess.Multiprocess . This is written to set a method thus called as the handler of the SIGUSR1 signal. Make the method run signal.siginterrupt(signal.SIGUSR1, False) and then send SIGUSR1 to each of its self.processes.
2. Monkey patch uvicorn.server.Server.startup to include a line

   loop.add_signal_handler(
       signal.SIGUSR1,
       getattr(self.config.loaded_app.app.state, 'method_to_do_the_task')
   )

3. Make sure to add this method to self.config.loaded_app.app.state or somewhere known to the app.