数据库 在使用mybatis插入大量数据的时候,为了提高效率,放弃循环插入,改为批量插入,mapper如下:
package com.lcy.service.mapper;
import com.lcy.service.pojo.TestVO;
import org.apache.ibatis.annotations.Insert;
import java.util.List;
public interface TestMapper {
@Insert("")
Integer testBatchInsert(List list);
}实体类:
package com.lcy.service.pojo;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@NoArgsConstructor
@AllArgsConstructor
public class TestVO {
private String t1;
private String t2;
private String t3;
private String t4;
private String t5;
}测试类如下:
import com.lcy.service.TestApplication;
import com.lcy.service.mapper.TestMapper;
import com.lcy.service.pojo.TestVO;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.ArrayList;
import java.util.List;
@SpringBootTest(classes = TestApplication.class)
@RunWith(SpringRunner.class)
public class TestDemo {
@Autowired
private TestMapper testMapper;
@Test
public void insert() {
List list = new ArrayList<>();
for (int i = 0; i < 200000; i++) {
list.add(new TestVO(i + "," + i, i + "," + i, i + "," + i, i + "," + i, i + "," + i));
}
System.out.println(testMapper.testBatchInsert(list));
}
}为了复现bug,我限制了JVM内存:
执行测试类报错如下:
java.lang.OutOfMemoryError: Java heap space
at java.base/java.util.Arrays.copyOf(Arrays.java:3746)
可以看到,Arrays在申请内存的时候,导致栈内存溢出
改进方法,分批新增:
import com.lcy.service.TestApplication;
import com.lcy.service.mapper.TestMapper;
import com.lcy.service.pojo.TestVO;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import javax.swing.*;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
@SpringBootTest(classes = TestApplication.class)
@RunWith(SpringRunner.class)
public class TestDemo {
@Autowired
private TestMapper testMapper;
@Test
public void insert() {
List list = new ArrayList<>();
for (int i = 0; i < 200000; i++) {
list.add(new TestVO(i + "," + i, i + "," + i, i + "," + i, i + "," + i, i + "," + i));
}
int index = list.size() / 10000;
for (int i=0;i< index;i++){
//stream流表达式，skip表示跳过前i*10000条记录，limit表示读取当前流的前10000条记录
testMapper.testBatchInsert(list.stream().skip(i*10000).limit(10000).collect(Collectors.toList()));
}
}
}还有一种方法是调高JVM内存,不过不建议使用,不仅吃内存,而且数据量过大会导致sql过长报错
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