Barrier

Source and Output

"""Example: barrier."""

from asimpy import Barrier, Environment, Process
from _util import example

NUM_WAITERS = 3  # number of waiting processes


class Waiter(Process):
    def init(self, barrier, delay):
        self._barrier = barrier
        self._delay = delay

    async def run(self):
        await self.timeout(self._delay)
        self._env.log(f"waiter {self._delay}", "waiting")
        await self._barrier.wait()
        self._env.log(f"waiter {self._delay}", "released")


class Releaser(Process):
    def init(self, barrier, delay):
        self._barrier = barrier
        self._delay = delay

    async def run(self):
        await self.timeout(self._delay)
        self._env.log("releaser", "releasing")
        self._barrier.release()


def main():
    env = Environment()
    barrier = Barrier(env)
    for i in range(NUM_WAITERS):
        Waiter(env, barrier, i)
    Releaser(env, barrier, NUM_WAITERS)
    env.run()
    return env


if __name__ == "__main__":
    example(main)

Key Points

1. Waiter processes all arrive at the barrier before the Releaser releases it.

2. Barrier.release() is not an async operation, so Waiter doesn't release it.

Check for Understanding

What would happen to a Waiter that called barrier.wait() after it was released?