java多線程批量拆分List導入數據庫的實現過程
一、前言
前兩天做瞭一個導入的功能,導入開始的時候非常慢,導入2w條數據要1分多鐘,後來一點一點的優化,從直接把list懟進Mysql中,到分配把list導入Mysql中,到多線程把list導入Mysql中。時間是一點一點的變少瞭。非常的爽,最後變成瞭10s以內。下面就展示一下過程。
二、直接把list懟進Mysql
使用mybatis的批量導入操作:
@Transactional(rollbackFor = Exception.class) public int addFreshStudentsNew2(List<FreshStudentAndStudentModel> list, String schoolNo) { if (list == null || list.isEmpty()) { return 0; } List<StudentEntity> studentEntityList = new LinkedList<>(); List<EnrollStudentEntity> enrollStudentEntityList = new LinkedList<>(); List<AllusersEntity> allusersEntityList = new LinkedList<>(); for (FreshStudentAndStudentModel freshStudentAndStudentModel : list) { EnrollStudentEntity enrollStudentEntity = new EnrollStudentEntity(); StudentEntity studentEntity = new StudentEntity(); BeanUtils.copyProperties(freshStudentAndStudentModel, studentEntity); BeanUtils.copyProperties(freshStudentAndStudentModel, enrollStudentEntity); String operator = TenancyContext.UserID.get(); String studentId = BaseUuidUtils.base58Uuid(); enrollStudentEntity.setId(BaseUuidUtils.base58Uuid()); enrollStudentEntity.setStudentId(studentId); enrollStudentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard()); enrollStudentEntity.setOperator(operator); studentEntity.setId(studentId); studentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard()); studentEntity.setOperator(operator); studentEntityList.add(studentEntity); enrollStudentEntityList.add(enrollStudentEntity); AllusersEntity allusersEntity = new AllusersEntity(); allusersEntity.setId(enrollStudentEntity.getId()); allusersEntity.setUserCode(enrollStudentEntity.getNemtCode()); allusersEntity.setUserName(enrollStudentEntity.getName()); allusersEntity.setSchoolNo(schoolNo); allusersEntity.setTelNum(enrollStudentEntity.getTelNum()); allusersEntity.setPassword(enrollStudentEntity.getNemtCode()); //密碼設置為考生號 allusersEntityList.add(allusersEntity); } enResult = enrollStudentDao.insertAll(enrollStudentEntityList); stuResult = studentDao.insertAll(studentEntityList); allResult = allusersFacade.insertUserList(allusersEntityList); if (enResult > 0 && stuResult > 0 && allResult) { return 10; } return -10; }
Mapper.xml
<insert id="insertAll" parameterType="com.dmsdbj.itoo.basicInfo.entity.EnrollStudentEntity"> insert into tb_enroll_student <trim prefix="(" suffix=")" suffixOverrides=","> id, remark, nEMT_aspiration, nEMT_code, nEMT_score, student_id, identity_card_id, level, major, name, nation, secondary_college, operator, sex, is_delete, account_address, native_place, original_place, used_name, pictrue, join_party_date, political_status, tel_num, is_registry, graduate_school, create_time, update_time </trim> values <foreach collection="list" item="item" index="index" separator=","> ( #{item.id,jdbcType=VARCHAR}, #{item.remark,jdbcType=VARCHAR}, #{item.nemtAspiration,jdbcType=VARCHAR}, #{item.nemtCode,jdbcType=VARCHAR}, #{item.nemtScore,jdbcType=VARCHAR}, #{item.studentId,jdbcType=VARCHAR}, #{item.identityCardId,jdbcType=VARCHAR}, #{item.level,jdbcType=VARCHAR}, #{item.major,jdbcType=VARCHAR}, #{item.name,jdbcType=VARCHAR}, #{item.nation,jdbcType=VARCHAR}, #{item.secondaryCollege,jdbcType=VARCHAR}, #{item.operator,jdbcType=VARCHAR}, #{item.sex,jdbcType=VARCHAR}, 0, #{item.accountAddress,jdbcType=VARCHAR}, #{item.nativePlace,jdbcType=VARCHAR}, #{item.originalPlace,jdbcType=VARCHAR}, #{item.usedName,jdbcType=VARCHAR}, #{item.pictrue,jdbcType=VARCHAR}, #{item.joinPartyDate,jdbcType=VARCHAR}, #{item.politicalStatus,jdbcType=VARCHAR}, #{item.telNum,jdbcType=VARCHAR}, #{item.isRegistry,jdbcType=TINYINT}, #{item.graduateSchool,jdbcType=VARCHAR}, now(), now() ) </foreach> </insert>
代碼說明:
底層的mapper是通過逆向工程來生成的,批量插入如下,是拼接成類似: insert into tb_enroll_student()values (),()…….() ;
這樣的缺點是,數據庫一般有一個默認的設置,就是每次sql操作的數據不能超過4M。這樣插入,數據多的時候,數據庫會報錯Packet for query is too large (6071393 > 4194304). You can change this value on the server by setting the max_allowed_packet’ variable.,雖然我們可以通過
類似 修改 my.ini 加上 max_allowed_packet =67108864
67108864=64M
默認大小4194304 也就是4M
修改完成之後要重啟mysql服務,如果通過命令行修改就不用重啟mysql服務。
完成本次操作,但是我們不能保證項目單次最大的大小是多少,這樣是有弊端的。所以可以考慮進行分組導入。
三、分組把list導入Mysql中
同樣適用mybatis批量插入,區別是對每次的導入進行分組計算,然後分多次進行導入:
@Transactional(rollbackFor = Exception.class) public int addFreshStudentsNew2(List<FreshStudentAndStudentModel> list, String schoolNo) { if (list == null || list.isEmpty()) { return 0; } List<StudentEntity> studentEntityList = new LinkedList<>(); List<EnrollStudentEntity> enrollStudentEntityList = new LinkedList<>(); List<AllusersEntity> allusersEntityList = new LinkedList<>(); for (FreshStudentAndStudentModel freshStudentAndStudentModel : list) { EnrollStudentEntity enrollStudentEntity = new EnrollStudentEntity(); StudentEntity studentEntity = new StudentEntity(); BeanUtils.copyProperties(freshStudentAndStudentModel, studentEntity); BeanUtils.copyProperties(freshStudentAndStudentModel, enrollStudentEntity); String operator = TenancyContext.UserID.get(); String studentId = BaseUuidUtils.base58Uuid(); enrollStudentEntity.setId(BaseUuidUtils.base58Uuid()); enrollStudentEntity.setStudentId(studentId); enrollStudentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard()); enrollStudentEntity.setOperator(operator); studentEntity.setId(studentId); studentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard()); studentEntity.setOperator(operator); studentEntityList.add(studentEntity); enrollStudentEntityList.add(enrollStudentEntity); AllusersEntity allusersEntity = new AllusersEntity(); allusersEntity.setId(enrollStudentEntity.getId()); allusersEntity.setUserCode(enrollStudentEntity.getNemtCode()); allusersEntity.setUserName(enrollStudentEntity.getName()); allusersEntity.setSchoolNo(schoolNo); allusersEntity.setTelNum(enrollStudentEntity.getTelNum()); allusersEntity.setPassword(enrollStudentEntity.getNemtCode()); //密碼設置為考生號 allusersEntityList.add(allusersEntity); } int c = 100; int b = enrollStudentEntityList.size() / c; int d = enrollStudentEntityList.size() % c; int enResult = 0; int stuResult = 0; boolean allResult = false; for (int e = c; e <= c * b; e = e + c) { enResult = enrollStudentDao.insertAll(enrollStudentEntityList.subList(e - c, e)); stuResult = studentDao.insertAll(studentEntityList.subList(e - c, e)); allResult = allusersFacade.insertUserList(allusersEntityList.subList(e - c, e)); } if (d != 0) { enResult = enrollStudentDao.insertAll(enrollStudentEntityList.subList(c * b, enrollStudentEntityList.size())); stuResult = studentDao.insertAll(studentEntityList.subList(c * b, studentEntityList.size())); allResult = allusersFacade.insertUserList(allusersEntityList.subList(c * b, allusersEntityList.size())); } if (enResult > 0 && stuResult > 0 && allResult) { return 10; } return -10; }
代碼說明:
這樣操作,可以避免上面的錯誤,但是分多次插入,無形中就增加瞭操作實踐,很容易超時。所以這種方法還是不值得提倡的。
再次改進,使用多線程分批導入。
四、多線程分批導入Mysql
依然使用mybatis的批量導入,不同的是,根據線程數目進行分組,然後再建立多線程池,進行導入。
@Transactional(rollbackFor = Exception.class) public int addFreshStudentsNew(List<FreshStudentAndStudentModel> list, String schoolNo) { if (list == null || list.isEmpty()) { return 0; } List<StudentEntity> studentEntityList = new LinkedList<>(); List<EnrollStudentEntity> enrollStudentEntityList = new LinkedList<>(); List<AllusersEntity> allusersEntityList = new LinkedList<>(); list.forEach(freshStudentAndStudentModel -> { EnrollStudentEntity enrollStudentEntity = new EnrollStudentEntity(); StudentEntity studentEntity = new StudentEntity(); BeanUtils.copyProperties(freshStudentAndStudentModel, studentEntity); BeanUtils.copyProperties(freshStudentAndStudentModel, enrollStudentEntity); String operator = TenancyContext.UserID.get(); String studentId = BaseUuidUtils.base58Uuid(); enrollStudentEntity.setId(BaseUuidUtils.base58Uuid()); enrollStudentEntity.setStudentId(studentId); enrollStudentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard()); enrollStudentEntity.setOperator(operator); studentEntity.setId(studentId); studentEntity.setIdentityCardId(freshStudentAndStudentModel.getIdCard()); studentEntity.setOperator(operator); studentEntityList.add(studentEntity); enrollStudentEntityList.add(enrollStudentEntity); AllusersEntity allusersEntity = new AllusersEntity(); allusersEntity.setId(enrollStudentEntity.getId()); allusersEntity.setUserCode(enrollStudentEntity.getNemtCode()); allusersEntity.setUserName(enrollStudentEntity.getName()); allusersEntity.setSchoolNo(schoolNo); allusersEntity.setTelNum(enrollStudentEntity.getTelNum()); allusersEntity.setPassword(enrollStudentEntity.getNemtCode()); //密碼設置為考生號 allusersEntityList.add(allusersEntity); }); int nThreads = 50; int size = enrollStudentEntityList.size(); ExecutorService executorService = Executors.newFixedThreadPool(nThreads); List<Future<Integer>> futures = new ArrayList<Future<Integer>>(nThreads); for (int i = 0; i < nThreads; i++) { final List<EnrollStudentEntity> EnrollStudentEntityImputList = enrollStudentEntityList.subList(size / nThreads * i, size / nThreads * (i + 1)); final List<StudentEntity> studentEntityImportList = studentEntityList.subList(size / nThreads * i, size / nThreads * (i + 1)); final List<AllusersEntity> allusersEntityImportList = allusersEntityList.subList(size / nThreads * i, size / nThreads * (i + 1)); Callable<Integer> task1 = () -> { studentSave.saveStudent(EnrollStudentEntityImputList,studentEntityImportList,allusersEntityImportList); return 1; }; futures.add(executorService.submit(task1)); } executorService.shutdown(); if (!futures.isEmpty() && futures != null) { return 10; } return -10; }
代碼說明:
上面是通過應用ExecutorService 建立瞭固定的線程數,然後根據線程數目進行分組,批量依次導入。一方面可以緩解數據庫的壓力,另一個面線程數目多瞭,一定程度會提高程序運行的時間。缺點就是要看服務器的配置,如果配置好的話就可以開多點線程,配置差的話就開小點。
五、小結
通過使用這個操作真是不斷的提高瞭,項目使用技巧也是不錯。加油~~ 多線程哦~~
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