tractor/examples/concurrent_actors_primes.py

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"""
Demonstration of the prime number detector example from the
``concurrent.futures`` docs:
https://docs.python.org/3/library/concurrent.futures.html#processpoolexecutor-example
This uses no extra threads or fancy semaphores besides ``tractor``'s
(TCP) channels.
"""
from contextlib import asynccontextmanager
from typing import List, Callable
import itertools
import math
import time
import tractor
import trio
PRIMES = [
112272535095293,
112582705942171,
112272535095293,
115280095190773,
115797848077099,
1099726899285419]
def is_prime(n):
if n < 2:
return False
if n == 2:
return True
if n % 2 == 0:
return False
sqrt_n = int(math.floor(math.sqrt(n)))
for i in range(3, sqrt_n + 1, 2):
if n % i == 0:
return False
return True
@asynccontextmanager
async def worker_pool(workers=4):
"""Though it's a trivial special case for ``tractor``, the well
known "worker pool" seems to be the defacto "I want this process
pattern" for most parallelism pilgrims.
"""
async with tractor.open_nursery() as tn:
portals = []
results = []
for i in range(workers):
# this starts a new sub-actor (process + trio runtime) and
# stores it's "portal" for later use to "submit jobs" (ugh).
portals.append(
await tn.start_actor(
f'worker_{i}',
rpc_module_paths=[__name__],
)
)
async def map(
worker_func: Callable[[int], bool],
sequence: List[int]
) -> List[bool]:
# define an async (local) task to collect results from workers
async def collect_portal_result(func, value, portal):
results.append((value, await portal.run(func, n=value)))
async with trio.open_nursery() as n:
for value, portal in zip(sequence, itertools.cycle(portals)):
n.start_soon(
collect_portal_result,
worker_func,
value,
portal
)
return results
yield map
# tear down all "workers"
await tn.cancel()
async def main():
async with worker_pool() as actor_map:
start = time.time()
# for number, prime in zip(PRIMES, executor.map(is_prime, PRIMES)):
for number, prime in await actor_map(is_prime, PRIMES):
print(f'{number} is prime: {prime}')
print(f'processing took {time.time() - start} seconds')
if __name__ == '__main__':
start = time.time()
tractor.run(
main,
loglevel='ERROR',
# uncomment to use ``multiprocessing`` fork server backend
# which gives a startup time boost at the expense of nested
# processs scalability
# start_method='forkserver')
)
print(f'script took {time.time() - start} seconds')