private void initWriteBufferWaterMark() {
        // init with system properties
        Integer lowWaterMarkConfig = ConfigManager.netty_buffer_low_watermark();
        if (lowWaterMarkConfig != null) {
            configuration.option(BoltServerOption.NETTY_BUFFER_LOW_WATER_MARK, lowWaterMarkConfig);
        }
        Integer highWaterMarkConfig = ConfigManager.netty_buffer_high_watermark();
        if (highWaterMarkConfig != null) {
            configuration
                .option(BoltServerOption.NETTY_BUFFER_HIGH_WATER_MARK, highWaterMarkConfig);
        }

        int lowWaterMark = configuration.option(BoltGenericOption.NETTY_BUFFER_LOW_WATER_MARK);
        int highWaterMark = configuration.option(BoltGenericOption.NETTY_BUFFER_HIGH_WATER_MARK);
        if (lowWaterMark > highWaterMark) {
            throw new IllegalArgumentException(
                String
                    .format(
                        "[client side] bolt netty high water mark {%s} should not be smaller than low water mark {%s} bytes)",
                        highWaterMark, lowWaterMark));
        } else {
            logger.warn(
                "[client side] bolt netty low water mark is {} bytes, high water mark is {} bytes",
                lowWaterMark, highWaterMark);
        }
        this.bootstrap.option(ChannelOption.WRITE_BUFFER_WATER_MARK, new WriteBufferWaterMark(
            lowWaterMark, highWaterMark));
    }
init netty write buffer water mark
src/main/java/com/alipay/remoting/connection/AbstractConnectionFactory.java