code: protected void initClientRunnable(ThreadPoolExecutor initPool, final CountDownLatch latch,
                                        final ProviderInfo providerInfo) {
          final ClientTransportConfig config = providerToClientConfig(providerInfo);
          initPool.execute(new Runnable() {
              @Override
              public void run() {
                  ClientTransport transport = ClientTransportFactory.getClientTransport(config);
                  if (consumerConfig.isLazy()) {
                      uninitializedConnections.put(providerInfo, transport);
                      latch.countDown();
                  } else {
                      try {
                          initClientTransport(consumerConfig.getInterfaceId(), providerInfo, transport);
                      } finally {
                          latch.countDown(); // 连上或者抛异常
                      }
                  }
              }
          });
      }
docs: 线程池建立长连接