Python gRPC服务器未在指定端口上侦听

Question

I'm trying to make a gRPC python server-client application following this example but I can't put the server on my code on a listening state. After adding the code almost as exactly equals to the example and running the start method yet nothing is listening on the port specified. My code is:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import grpc
import interface_pb2
import interface_pb2_grpc
from concurrent import futures
import time
# some other imports...

class GrpcInterface(interface_pb2_grpc.ManipulaMapaServicer):
    def CriaItem(self, request, context):
        # do stuff...

    def LeItem(self, request, context):
        # do stuff...

    def AtualizaItem(self, request, context):
        # do stuff...

    def DeletaItem(self, request, context):
        # do stuff...

_ONE_DAY_IN_SECONDS = 60 * 60 * 24

def main():
    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
    interface_pb2_grpc.add_ManipulaMapaServicer_to_server(GrpcInterface(), server)
    print('Vai iniciar o servidor gRPC na porta ' + str(8888))
    server.add_insecure_port('[::]:' + str(8888))
    server.start()
    try:
        while True:
            time.sleep(_ONE_DAY_IN_SECONDS)
    except KeyboardInterrupt:
        server.stop(0)

if __name__ == '__main__':
    try:
        main()
    except Exception as e:
        print('Erro ao rodar servidor: ')
        print(str(e))

The code for interface_pb2_grpc.ManipulaMapaServicer are of course auto generated (with the command python3 -m grpc_tools.protoc -I . --python_out=. --grpc_python_out=. interface.proto ) based on my interface.proto :

syntax = "proto3";

message msgItem {
    int64 chave = 1;
    string valor = 2;
}

message status {
    string resposta = 1; 
    msgItem itemResposta = 2; 
}

service ManipulaMapa {
    rpc CriaItem (msgItem) returns (status) {}
    rpc LeItem (msgItem) returns (msgItem) {}
    rpc AtualizaItem (msgItem) returns (status) {}
    rpc DeletaItem (msgItem) returns (status) {}
}

The execution reaches the while True: loop inside main yet no server running on port 8888 . What can be wrong here? By the way, this question is not duplicate from this one because in this last question the problem was caused by a garbage collector that ran right after the start method.

Answer 1

You can try to enable logging before calling main(). If there is anything wrong during the server.start() calling, it will write error logs.

That is, add this before main().

logging.basicConfig()

For instance, if the port is already listening by other processes.

E0830 19:35:33.731000000 55600 src/core/ext/transport/chttp2/server/insecure/server_chttp2.cc:40] {"created":"@1567164933.731000000","description":"No address added out of total 1 resolved","file":"src/core/ext/transport/chttp2/server/chttp2_server.cc","file_line":394,"referenced_errors":[{"created":"@1567164933.731000000","description":"Failed to add port to server","file":"src/core/lib/iomgr/tcp_server_windows.cc","file_line":510,"referenced_errors":[{"created":"@1567164933.731000000","description":"OS Error","file":"src/core/lib/iomgr/tcp_server_windows.cc","file_line":201,"os_error":"Only one usage of each socket address (protocol/network address/port) is normally permitted.\r\n","syscall":"bind","wsa_error":10048}]}]}