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# Copyright 2019 gRPC authors.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""An example of multiprocess concurrency with gRPC."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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from concurrent import futures
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import contextlib
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import datetime
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import logging
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import math
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import multiprocessing
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import socket
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import sys
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import time
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import grpc
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import prime_pb2
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import prime_pb2_grpc
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_LOGGER = logging.getLogger(__name__)
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_ONE_DAY = datetime.timedelta(days=1)
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_PROCESS_COUNT = multiprocessing.cpu_count()
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_THREAD_CONCURRENCY = _PROCESS_COUNT
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def is_prime(n):
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for i in range(2, int(math.ceil(math.sqrt(n)))):
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if n % i == 0:
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return False
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else:
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return True
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class PrimeChecker(prime_pb2_grpc.PrimeCheckerServicer):
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def check(self, request, context):
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_LOGGER.info("Determining primality of %s", request.candidate)
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return prime_pb2.Primality(isPrime=is_prime(request.candidate))
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def _wait_forever(server):
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try:
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while True:
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time.sleep(_ONE_DAY.total_seconds())
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except KeyboardInterrupt:
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server.stop(None)
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def _run_server(bind_address):
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"""Start a server in a subprocess."""
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_LOGGER.info("Starting new server.")
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options = (("grpc.so_reuseport", 1),)
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server = grpc.server(
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futures.ThreadPoolExecutor(
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max_workers=_THREAD_CONCURRENCY,
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),
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options=options,
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)
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prime_pb2_grpc.add_PrimeCheckerServicer_to_server(PrimeChecker(), server)
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server.add_insecure_port(bind_address)
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server.start()
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_wait_forever(server)
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@contextlib.contextmanager
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def _reserve_port():
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"""Find and reserve a port for all subprocesses to use."""
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sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
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sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT, 1)
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if sock.getsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT) == 0:
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raise RuntimeError("Failed to set SO_REUSEPORT.")
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sock.bind(("", 0))
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try:
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yield sock.getsockname()[1]
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finally:
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sock.close()
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def main():
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with _reserve_port() as port:
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bind_address = "localhost:{}".format(port)
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_LOGGER.info("Binding to '%s'", bind_address)
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sys.stdout.flush()
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workers = []
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for _ in range(_PROCESS_COUNT):
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# NOTE: It is imperative that the worker subprocesses be forked before
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# any gRPC servers start up. See
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# https://github.com/grpc/grpc/issues/16001 for more details.
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worker = multiprocessing.Process(
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target=_run_server, args=(bind_address,)
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)
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worker.start()
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workers.append(worker)
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for worker in workers:
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worker.join()
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if __name__ == "__main__":
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handler = logging.StreamHandler(sys.stdout)
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formatter = logging.Formatter("[PID %(process)d] %(message)s")
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handler.setFormatter(formatter)
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_LOGGER.addHandler(handler)
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_LOGGER.setLevel(logging.INFO)
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main()
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