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@AllArgsConstructorpublic 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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