1# Copyright 2024 gRPC authors. 2# 3# Licensed under the Apache License, Version 2.0 (the "License"); 4# you may not use this file except in compliance with the License. 5# You may obtain a copy of the License at 6# 7# http://www.apache.org/licenses/LICENSE-2.0 8# 9# Unless required by applicable law or agreed to in writing, software 10# distributed under the License is distributed on an "AS IS" BASIS, 11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12# See the License for the specific language governing permissions and 13# limitations under the License. 14"""Example gRPC server that applies back-pressure on client""" 15 16from concurrent import futures 17import logging 18import time 19 20import grpc 21import helloworld_pb2 22import helloworld_pb2_grpc 23import helpers 24 25_PORT = "50051" 26 27 28class Greeter(helloworld_pb2_grpc.GreeterServicer): 29 def SayHelloBidiStream(self, request_iterator, unused_context): 30 # Delay read on server side to apply back-pressure on client 31 time.sleep(5) 32 33 bytes_received = 0 34 35 # Read request from client on every iteration 36 for i, request in enumerate(request_iterator, start=1): 37 bytes_received += len(request.name) 38 if (i % 10) == 0: 39 print( 40 f"{helpers.get_current_time()} " 41 f"Request {i}: Received {bytes_received} bytes in total" 42 ) 43 44 # Simulate server "work" 45 time.sleep(1) 46 47 # Send a response 48 msg = "Hello!" 49 yield helloworld_pb2.HelloReply(message=msg) 50 51 if (i % 10) == 0: 52 print( 53 f"{helpers.get_current_time()} " 54 f"Request {i}: Sent {bytes_received} bytes in total\n" 55 ) 56 57 58def serve(): 59 server = grpc.server( 60 futures.ThreadPoolExecutor(max_workers=10), 61 # Setting server options to minimal, to allow low number of maximum 62 # bytes in the window. 63 # `bdp_probe` is set to 0(false) to disable resizing of window 64 options=[ 65 ("grpc.http2.max_frame_size", 16384), 66 ("grpc.http2.bdp_probe", 0), 67 ("grpc.max_concurrent_streams", 1), 68 ], 69 ) 70 helloworld_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server) 71 72 server.add_insecure_port("[::]:" + _PORT) 73 server.start() 74 print("Server started, listening on " + _PORT) 75 server.wait_for_termination() 76 77 78if __name__ == "__main__": 79 logging.basicConfig() 80 serve() 81