How to interrupt nested processes in SimPy?

Question

I'm trying to interrupt a set of nested processes in simpy. It appears from the following code that only the first layer of processes is interrupted by an interrupt event, and I can't seem to find a way to reference the processes defined within another process from outside the outer process in order to interrupt them. Below is a minimum reproducible example:

import simpy

env = simpy.Environment()

def process_one():
    try:
        yield env.timeout(5)
        print("inside process one")
        yield env.process(process_two())
        yield env.timeout(10)
    except simpy.Interrupt:
        print("interrupted at ", env.now)

def process_two():
    try:
        yield env.timeout(5)
        print("inside process two")
        yield env.timeout(5)
        print("finishing process two")
    except simpy.Interrupt:
        print("process two interrupted at", env.now)

process = env.process(process_one())


def interruption(time):
    yield env.timeout(time)
    process.interrupt()

env.process(interruption(6))

env.run(until=30)

Process one gets interrupted as it should, but process two continues on its business. If I assign env.process(process_two) to a variable inside process_one, I can't access it from outside the scope of process_one. Is there a way to cause an interruption to interrupt all ongoing processes defined within a parent process, or do all processes in simpy have to be defined only one layer deep?

Answer 1

Only the process on which you call interrupt() gets interrupted. To interrupt the second process, you need a reference to it:

If you want to interrupt the currently active process, use Environment.active_process to get a ref to it.

If you want to explicitly interrupt the second process, store a ref to it somewhere in a shated namespace.

Finally, you can also catch the interrupt in process one and forward it to process two. Process one can than continue to work (if it wants to).