Designing a Bounded FIFO Export Queue for Large MySQL Data Exports in Java Spring

This article addresses the performance impact of exporting large volumes of MySQL data by introducing a bounded FIFO queue that serializes export tasks, limits concurrent operations, and integrates with EasyExcel for efficient file generation.

Business Requirements

The system must handle full‑data exports that involve heavy MySQL I/O and file stream operations, which can strain server resources when multiple users export simultaneously. A fixed‑size queue is proposed to serialize export requests and record export metadata.

Domain Model

ExportQueue : Maintains a fixed‑size queue, provides methods to add users, retrieve the next user, and blocks when the queue is full.

UserInfo : Represents the user who initiates an export.

Export : Defines the export method, supports asynchronous execution, and allows users to download generated files.

ExportQueue Implementation

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; // queue max size
    private LinkedList
queue;

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

    /**
     * Add a user to the queue
     */
    public synchronized LinkedList
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;
    }

    /**
     * Get the next user from the queue
     */
    public synchronized ExportUser getNextSysUser() {
        while (queue.isEmpty()) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        ExportUser sysUser = queue.remove();
        notifyAll(); // wake up waiting threads
        return sysUser;
    }
}

AbstractExport (EasyExcel Integration)

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
{
    public abstract void export(ExportUser sysUser) throws InterruptedException;

    /**
     * Export data to Excel
     */
    public void export(HttpServletResponse response, int pageSize, T t, Class
k, String fileName) throws Exception {
        ExcelWriter writer = null;
        try {
            writer = getExcelWriter(response, fileName);
            int total = this.countExport(t);
            int loopCount = PageUtil.totalPage(total, pageSize);
            BeanUtil.setProperty(t, "pageSize", pageSize);
            for (int i = 0; i < loopCount; i++) {
                BeanUtil.setProperty(t, "pageNum", PageUtil.getStart(i + 1, pageSize));
                List
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");
        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();
    }

    public abstract void complexFillWithTable(T t, String fileName, HttpServletResponse response);
    public abstract int countExport(T t);
    public abstract List
getExportDetail(T t);
}

ExportImpl (Concrete Service)

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 {
        log.info("导出文件方法执行～～～～～～～～～");
        LinkedList
queue = exportQueue.add(sysUser);
        log.info("导出队列：" + queue);
        Thread.sleep(20000); // simulate export processing time
        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) {
        // not implemented
    }

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

    @Override
    public List getExportDetail(Object o) {
        return null;
    }
}

Test Controller

package com.example.system.controller;

import com.example.system.api.domain.ExportUser;
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.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();
    }
}

Test Results

The queue size is limited to 10. When the limit is reached, additional export requests are blocked until a slot becomes free. Logs and screenshots show that the first request finishes after ~20 seconds, the next user is then dequeued and processed, confirming FIFO behavior.

Conclusion

While the presented implementation demonstrates a workable FIFO export queue, it does not yet cover file schema design, OSS storage, download endpoints, or high‑concurrency edge cases. Alternative approaches such as Redis‑based queues are also viable.