add examples of name resolve and load balance

[Smityz]

Ref: #9691
I add an example of name resolve and load balance.

[linux-foundation-easycla]

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• ✅ login: Smityz / name: Smilencer (c065b80, 52277a3)

[Smityz]

WARNING: RPC failed: Status{code=INTERNAL, description=Panic! This is a bug!, cause=java.lang.IllegalStateException: Could not find policy 'round_robin'. Make sure its implementation is either registered to LoadBalancerRegistry or included in META-INF/services/io.grpc.LoadBalancerProvider from your jar files.
        at io.grpc.internal.AutoConfiguredLoadBalancerFactory$AutoConfiguredLoadBalancer.<init>(AutoConfiguredLoadBalancerFactory.java:94)
        at io.grpc.internal.AutoConfiguredLoadBalancerFactory.newLoadBalancer(AutoConfiguredLoadBalancerFactory.java:61)
        at io.grpc.internal.ManagedChannelImpl.exitIdleMode(ManagedChannelImpl.java:412)
        at io.grpc.internal.ManagedChannelImpl$RealChannel$2.run(ManagedChannelImpl.java:981)
        at io.grpc.SynchronizationContext.drain(SynchronizationContext.java:95)
        at io.grpc.SynchronizationContext.execute(SynchronizationContext.java:127)
        at io.grpc.internal.ManagedChannelImpl$RealChannel.newCall(ManagedChannelImpl.java:978)
        at io.grpc.internal.ManagedChannelImpl.newCall(ManagedChannelImpl.java:920)
        at io.grpc.internal.ForwardingManagedChannel.newCall(ForwardingManagedChannel.java:63)
        at io.grpc.stub.ClientCalls.blockingUnaryCall(ClientCalls.java:150)
        at io.grpc.examples.helloworld.GreeterGrpc$GreeterBlockingStub.sayHello(GreeterGrpc.java:157)
        at io.grpc.examples.loadbalance.LoadBalanceClient.greet(LoadBalanceClient.java:45)
        at io.grpc.examples.loadbalance.LoadBalanceClient.main(LoadBalanceClient.java:65)

This error happened when I use LoadBalanceClient which was compiled by Bazel, but Maven and Gradle are normal, I don't know how to fix it, can someone give a help?

[temawi]

Sorry for the delay in reviewing this! It's looking great, thanks for the extra effort to have it match the Go implementation.

Could we do one more change to have it match Go even closer? If you look at the Go codebase they have split this into two independent examples, "name_resolving" and "load_balancing". The idea is that a user wanting to just understand load balancing does not get confused with custom name resolution code and think they have to implement that as well.

You may have been hesitant to split the examples because both examples use the same server code, but in this case it would be fine to just copy the same implementation to both examples.

[temawi]

Thank you @Smityz this looks great!