背景

前端快速点击加减，反应迟缓
流程：前端->后端->plc
暗区改善后端需要给plc一次发送多次指令，但是日志显示

核心记忆

记住一点内存泄漏ChannelInboundHandlerAdapter 这个必须在读完释放掉bytebuf，具体如下代码所示，也就是添加ReferenceCountUtil.release(in);

chatgpt回答

即使您继承了 ChannelInboundHandlerAdapter，在您的自定义处理器中仍然需要负责释放 ByteBuf，以避免内存泄漏。当您继承了 SimpleChannelInboundHandler，Netty 会在处理完消息后自动释放 ByteBuf，因此您不需要手动调用 ReferenceCountUtil.release 来释放 ByteBuf。这是 SimpleChannelInboundHandler 的一个优点，它会自动帮助您管理资源，防止内存泄漏。

/**
 * WebServerHandler.java
 * Created at 2022-08-30
 * Copyright (C) 2022 WEGO Group, All rights reserved.
 */
package com.wg.server;

import cn.hutool.core.thread.ThreadUtil;
import cn.hutool.core.util.HexUtil;
import cn.hutool.core.util.ObjectUtil;
import com.wg.constant.Constants;
import com.wg.constant.HttpStatus;
import com.wg.util.MessageUtil;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;
import io.netty.util.ReferenceCountUtil;
import io.swagger.v3.oas.annotations.Operation;
import io.swagger.v3.oas.annotations.tags.Tag;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * <p>ClassName: WebServerHandler</p>
 * <p>Description: 主程序入口服务器消息处理器  </p>
 *
 * @author chenyuxiang
 * @date 2022-08-30
 */
@Slf4j
@Controller
@Tag(name = "确认连接")
@ChannelHandler.Sharable
public class WebServerHandler extends ChannelInboundHandlerAdapter {

    /** 接入的主程序入口服务 */
    public static final Map<String, ChannelHandlerContext> MASTER_MAP = new ConcurrentHashMap<>();

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        String uuid = ctx.channel().id().asLongText();
        MASTER_MAP.put(uuid, ctx);
        log.info("连接请求进入: {}， 地址: {}", uuid, ctx.channel().remoteAddress());
        super.channelActive(ctx);
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        String uuid = ctx.channel().id().asLongText();
        MASTER_MAP.remove(uuid);
        ctx.channel().close();
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf in = (ByteBuf) msg;
        try {
            byte[] bytes = new byte[Constants.MEG_LENGTH];
            in.readBytes(bytes);

            log.info("收到消息 --> {}", HexUtil.encodeHexStr(bytes));

            String msgId = HexUtil.encodeHexStr(new byte[]{bytes[Constants.MSG_ID_POS]});

            //处理CountDownLatch
            if (ObjectUtil.isNotNull(MessageUtil.MSG_ID_COUNT_DOWN_LATCH.get(msgId))){
                MessageUtil.MSG_ID_COUNT_DOWN_LATCH.get(msgId).countDown();
                MessageUtil.MSG_ID_COUNT_DOWN_LATCH.remove(msgId);
            }
        } finally {
            // 释放ByteBuf
            ReferenceCountUtil.release(in);
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        String uuid = ctx.channel().id().asLongText();
        MASTER_MAP.remove(uuid);
        log.error(cause.getMessage());
        ctx.close();
    }



}