Question On Sampler Strategy Changing

[winshenting]

In our scenario, our application is springboot. we configure sampler strategy rate limiting 2.0 in Collector.
in the client, we configure opentracing.jaeger.remote-controlled-sampler.host-port=localhost:5778
in theory , Client will get sampler strategy from Agent.
However, whenever we change value of rate limiting from 2.0 to 0.0 or 1.0. The client does not get the latest sampler strategy.
I wonder

1. why it does not work. Why client does not get correct sampler strategy effectively? Do I need to restart Collector to take configuration effectively?
2. Does Client get policy from agent and collector by interval or does collector push the policy to client by interval