if (grpcExecutor == null) {
    int threadNumber = ThreadUtils.getSuitableThreadCount(8);
    grpcExecutor = new ThreadPoolExecutor(threadNumber, threadNumber, 10L, TimeUnit.SECONDS,
            new LinkedBlockingQueue<>(10000),
            new ThreadFactoryBuilder().setDaemon(true).setNameFormat("nacos-grpc-client-executor-%d")
                    .build());
    grpcExecutor.allowCoreThreadTimeOut(true);
}
// 8848+1000
int port = serverInfo.getServerPort() + rpcPortOffset();
RequestGrpc.RequestFutureStub newChannelStubTemp = createNewChannelStub(serverInfo.getServerIp(), port);
// 发一个ServerCheckRequest请求验证服务端的可用性
Response response = serverCheck(serverInfo.getServerIp(), port, newChannelStubTemp);
if (response == null || !(response instanceof ServerCheckResponse)) {
    shuntDownChannel((ManagedChannel) newChannelStubTemp.getChannel());
    return null;
}

BiRequestStreamGrpc.BiRequestStreamStub biRequestStreamStub = BiRequestStreamGrpc
        .newStub(newChannelStubTemp.getChannel());
// 创建GrpcConnection对象，封装serverInfo和executor、connectionId、channel等
GrpcConnection grpcConn = new GrpcConnection(serverInfo, grpcExecutor);
grpcConn.setConnectionId(((ServerCheckResponse) response).getConnectionId());

// create stream request and bind connection event to this connection
StreamObserver<Payload> payloadStreamObserver = bindRequestStream(biRequestStreamStub, grpcConn);

// stream observer to send response to server
grpcConn.setPayloadStreamObserver(payloadStreamObserver);
grpcConn.setGrpcFutureServiceStub(newChannelStubTemp);
grpcConn.setChannel((ManagedChannel) newChannelStubTemp.getChannel());
// send a setup request
ConnectionSetupRequest conSetupRequest = new ConnectionSetupRequest();
conSetupRequest.setClientVersion(VersionUtils.getFullClientVersion());
conSetupRequest.setLabels(super.getLabels());
conSetupRequest.setAbilities(super.clientAbilities);
conSetupRequest.setTenant(super.getTenant());
grpcConn.sendRequest(conSetupRequest);

发送请求

Requester接口

这个接口定义了发送请求的方法：

public interface Requester {

    /**
     * send request.
     *
     * @param request      request.
     * @param timeoutMills mills of timeouts.
     * @return response  response returned.
     * @throws NacosException exception throw.
     */
    Response request(Request request, long timeoutMills) throws NacosException;

    /**
     * send request.
     *
     * @param request request.
     * @return request future.
     * @throws NacosException exception throw.
     */
    RequestFuture requestFuture(Request request) throws NacosException;

    /**
     * send async request.
     *
     * @param request         request.
     * @param requestCallBack callback of request.
     * @throws NacosException exception throw.
     */
    void asyncRequest(Request request, RequestCallBack requestCallBack) throws NacosException;

    /**
     * close connection.
     */
    void close();
}

GrpcConnection实现

GrpcConnection类实现了Requester接口的三个request方法，使用的是GRPC的Stub发送请求，以request方法为例：