Java多線程批量拆分List導(dǎo)入數(shù)據(jù)庫
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來源：urls.press/0X4zD
一、前言
前兩天做了一個導(dǎo)入的功能，導(dǎo)入開始的時候非常慢，導(dǎo)入2w條數(shù)據(jù)要1分多鐘，后來一點一點的優(yōu)化，從直接把list懟進Mysql中，到分配把list導(dǎo)入Mysql中，到多線程把list導(dǎo)入Mysql中。時間是一點一點的變少了。非常的爽，最后變成了10s以內(nèi)。下面就展示一下過程。
二、直接把list懟進Mysql
使用mybatis的批量導(dǎo)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(shè)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(shù)據(jù)庫一般有一個默認的設(shè)置，就是每次sql操作的數(shù)據(jù)不能超過4M。這樣插入，數(shù)據(jù)多的時候，數(shù)據(jù)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
修改完成之后要重啟mysql服務(wù)，如果通過命令行修改就不用重啟mysql服務(wù)。
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(dǎo)入。
三、分組把list導(dǎo)入Mysql中
同樣適用mybatis批量插入，區(qū)別是對每次的導(dǎo)入進行分組計算，然后分多次進行導(dǎo)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(shè)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，無形中就增加了操作實踐，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(dǎo)入。
四、多線程分批導(dǎo)入Mysql
依然使用mybatis的批量導(dǎo)入，不同的是，根據(jù)線程數(shù)目進行分組，然后再建立多線程池，進行導(dǎo)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(shè)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(yīng)用ExecutorService 建立了固定的線程數(shù)，然后根據(jù)線程數(shù)目進行分組，批量依次導(dǎo)入。一方面可以緩解數(shù)據(jù)庫的壓力，另一個面線程數(shù)目多了，一定程度會提高程序運行的時間。缺點就是要看服務(wù)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(jié)
通過使用這個操作真是不斷的提高了，項目使用技巧也是不錯。加油~~ 多線程哦~~
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