如何知道GRPC服务器是否可用

Question

If a gRPC client starts before the server, it exits with an exception. The application I am working on starts a bunch of servers and clients (near) simultaneously, however, and I have to be robust with respect to execution order. If the client starts before the server, I want it to wait until the server shows up.

I modified the HelloWorld python client example as follows:

done = False
while not done:
    try:
        response = stub.SayHello(helloworld_pb2.HelloRequest(name='you'), timeout=1)
        print("Greeter client received: " + response.message)
        done = True
    except:
        print('Waiting for server connect...')
        time.sleep(1)

so now if I start the client before the server, I get the 'Waiting for server connect...' message scrolling up my terminal window as expected. Then I start the server, and it connects... eventually. In fact it takes about ten seconds before the 'Hello you' messages appears, which is surprisingly long. Why might it be so slow, and is there a robust way to check for server connection?

Answer 1

import grpc

TIMEOUT_SEC = 15
def grpc_server_on(channel) -> bool:
    try:
        grpc.channel_ready_future(channel).result(timeout=TIMEOUT_SEC)
        return True
    except grpc.FutureTimeoutError:
        return False

该channel_ready_future函数允许客户端等待指定的超时持续时间（以秒为单位），以便服务器准备就绪。如果我们的客户端超时，它就会上升。

Answer 2

看看ChannelConnectivity-我是一名Go程序员，但在python中应该是相同的。我要做的是创建while while / for循环，并且当“ ChannelConnectivity”设置为“ READY”时，我从连接中创建客户端，然后继续。