How to Implement a FIFO Export Queue in Spring Boot to Prevent Performance Bottlenecks

Introduction

Business requirement: as database data grows, full‑data export can impact service performance due to MySQL I/O and file I/O, especially with concurrent exports. Therefore the export operation needs to be queued.

Initial idea: maintain a FIFO queue with a fixed size; users wait in line, export runs, then the user is dequeued. An asynchronous export table records file status and location for download.

Business Relationship Definition

Key entities: User, ExportQueue, Export execution method. ExportQueue maintains a fixed‑length queue, provides methods to query front/back users, and blocks when the queue is full. User information is associated with the export task. Export class defines the asynchronous export method and allows users to view/download files.

Implementation Details

ExportQueue

<code>package com.example.system.config;

import com.example.system.api.domain.ExportUser;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import java.util.LinkedList;

@Slf4j
@Component
public class ExportQueue {

    private final int MAX_CAPACITY = 10; // 队列最大容量
    private LinkedList<ExportUser> queue; // 用户队列

    public ExportQueue(LinkedList<ExportUser> queue) {
        this.queue = new LinkedList<>();
    }

    /**
     * 排队队列添加
     * @param sysUser
     */
    public synchronized LinkedList<ExportUser> add(ExportUser sysUser) {
        while (queue.size() >= MAX_CAPACITY) {
            try {
                log.info("当前排队人已满，请等待");
                wait();
            } catch (InterruptedException e) {
                e.getMessage();
            }
        }
        queue.add(sysUser);
        log.info("目前导出队列排队人数：" + queue.size());
        notifyAll();
        return queue;
    }

    /**
     * 获取排队队列下一个人
     * @return
     */
    public synchronized ExportUser getNextSysUser() {
        while (queue.isEmpty()) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        ExportUser sysUser = queue.remove();
        notifyAll(); //唤醒
        return sysUser;
    }
}
</code>

AbstractExport

Integrates EasyExcel for million‑row export.

<code>package com.example.system.config;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.PageUtil;
import com.alibaba.excel.EasyExcel;
import com.alibaba.excel.ExcelWriter;
import com.alibaba.excel.write.metadata.WriteSheet;
import com.example.system.api.domain.ExportUser;
import lombok.extern.slf4j.Slf4j;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLEncoder;
import java.util.List;

@Slf4j
public abstract class AbstractExport<T, K> {

    public abstract void export(ExportUser sysUser) throws InterruptedException;

    /**
     * 导出
     *
     * @param response 输出流
     * @param pageSize 每页大小
     * @param t        导出条件
     * @param k        Excel内容实体类
     * @param fileName 文件名称
     */
    public void export(HttpServletResponse response, int pageSize, T t, Class<K> k, String fileName) throws Exception {
        ExcelWriter writer = null;
        try {
            writer = getExcelWriter(response, fileName);
            //查询导出总条数
            int total = this.countExport(t);
            //页数
            int loopCount = PageUtil.totalPage(total, pageSize);
            BeanUtil.setProperty(t, "pageSize", pageSize);
            for (int i = 0; i < loopCount; i++) {
                //开始页
                BeanUtil.setProperty(t, "pageNum", PageUtil.getStart(i + 1, pageSize));
                //获取Excel导出信息
                List<K> kList = this.getExportDetail(t);
                WriteSheet writeSheet = EasyExcel.writerSheet(fileName).head(k).build();
                writer.write(kList, writeSheet);
            }
        } catch (Exception e) {
            String msg = "导出" + fileName + "异常";
            log.error(msg, e);
            throw new Exception(msg + e);
        } finally {
            if (writer != null) {
                writer.finish();
            }
        }
    }

    public ExcelWriter getExcelWriter(HttpServletResponse response, String fileName) throws IOException {
        response.setContentType("application/vnd.ms-excel");
        response.setCharacterEncoding("utf-8");
        // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系
        String fileNameUtf = URLEncoder.encode(fileName, "UTF-8").replaceAll("\\+", "%20");
        response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileNameUtf + ".xlsx");
        return EasyExcel.write(response.getOutputStream()).build();
    }

    /**
     * （模版导出）
     *
     * @param t
     * @param fileName
     * @param response
     */
    public abstract void complexFillWithTable(T t, String fileName, HttpServletResponse response);

    /**
     * 查询导出总条数
     *
     * @param t
     * @return
     */
    public abstract int countExport(T t);

    /**
     * 查询导出数据
     *
     * @param t
     * @return
     */
    public abstract List<K> getExportDetail(T t);
}
</code>

ExportImpl

<code>package com.example.system.service.impl;

import com.alibaba.excel.ExcelWriter;
import com.example.system.api.domain.ExportUser;
import com.example.system.config.AbstractExport;
import com.example.system.config.ExportQueue;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;

@Service
@Slf4j
public class ExportImpl extends AbstractExport {

    @Autowired
    private ExportQueue exportQueue;

    @Override
    public void export(ExportUser sysUser) throws InterruptedException {
        //导出
        log.info("导出文件方法执行～～～～～～～～～");
        //        export(response,pageSize,t,k,fileName);
        LinkedList<ExportUser> queue = exportQueue.add(sysUser);
        log.info("导出队列：" + queue);
        //休眠时间稍微设置大点，模拟导出处理时间
        Thread.sleep(20000);
        //导出成功后移除当前导出用户
        ExportUser nextSysUser = exportQueue.getNextSysUser();
        log.info("移除后获取下一个排队的用户: " + nextSysUser.getUserName());
    }

    @Override
    public void export(HttpServletResponse response, int pageSize, Object o, Class k, String fileName) throws Exception {
        super.export(response, pageSize, o, k, fileName);
    }

    @Override
    public ExcelWriter getExcelWriter(HttpServletResponse response, String fileName) throws IOException {
        return super.getExcelWriter(response, fileName);
    }

    @Override
    public void complexFillWithTable(Object o, String fileName, HttpServletResponse response) {
        // TODO: implement
    }

    @Override
    public int countExport(Object o) {
        return 0;
    }

    @Override
    public List getExportDetail(Object o) {
        return null;
    }
}
</code>

Test Controller

<code>package com.example.system.controller;

import com.example.system.api.domain.ExportUser;
import com.example.system.api.domain.SysUser;
import com.example.system.service.impl.ExportImpl;
import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/export")
@Slf4j
public class ExportController {

    @Autowired
    private ExportImpl export;

    @PostMapping("/exportFile")
    public void exportFile() {
        new Thread(new Runnable() {
            @SneakyThrows
            @Override
            public void run() {
                Thread thread1 = Thread.currentThread();
                ExportUser sysUser = new ExportUser();
                sysUser.setUserName(thread1.getName());
                export.export(sysUser);
            }
        }).start();
    }
}
</code>

Test Results

When the queue size exceeds the limit of 10, further submissions are blocked.

First and second requests spaced 10 seconds apart: after the first export finishes, the user is removed from the queue and the next user moves to the front.

Conclusion

Remaining tasks include designing the export file schema, OSS upload, download handling, and evaluating high‑concurrency issues. Alternative implementations such as a Redis queue are possible; this article provides one practical approach.