@Override
    public void operationComplete(ChannelFuture future) {
      if (!future.isSuccess()) {
        perfClientMetrics.connectError.inc();
        Channel channel = future.channel();
        logger.error("Channel {} to {} could not be connected.", channel, channel.remoteAddress(), future.cause());
      }
    }
Channel connection listener that prints error if channel could not be connected.
ambry-tools/src/main/java/com/github/ambry/tools/perf/rest/NettyPerfClient.java