WaitForReady in python

[Julian Gold]

I am working on an architecture with a single client and multiple servers. GRPC raises an exception if the client starts without a server present, so I tried modifying the HelloWorld sample to wait until a call succeeds:

  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)

Strangely, though this works, it takes quite a while to connect when the server is started after the client (about 10 seconds or more) before showing the result. A quick internet search shows there is a WaitForReady option in C#, but there doesn't seem to be an equivalent in Python? How else can I check if a connection is ready?


   

[Ken Payson]

There are a few ways to track channel state in Python. If you only want to block until it is connected, try

grpc.channel_ready_future(channel).result()

https://grpc.io/grpc/python/grpc.html#grpc.channel_ready_future

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[Julian Gold]

Thanks Ken, that looks useful!

On Friday, 18 August 2017 16:37:17 UTC+1, Ken Payson wrote:

There are a few ways to track channel state in Python. If you only want to block until it is connected, try

grpc.channel_ready_future(channel).result()

https://grpc.io/grpc/python/grpc.html#grpc.channel_ready_future

On Fri, Aug 18, 2017 at 7:23 AM, Julian Gold <julian.b...@gmail.com> wrote:

I am working on an architecture with a single client and multiple servers. GRPC raises an exception if the client starts without a server present, so I tried modifying the HelloWorld sample to wait until a call succeeds:

  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)

Strangely, though this works, it takes quite a while to connect when the server is started after the client (about 10 seconds or more) before showing the result. A quick internet search shows there is a WaitForReady option in C#, but there doesn't seem to be an equivalent in Python? How else can I check if a connection is ready?


   

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