统计JAVA对象占用Heap堆内存大小 – JMock

在开发过程中，一些超大Java对象需要存储到每一个后端服务的节点中。在实际操作过程中，放在Redis中，每次读取Key然后反序列化成Java对象的时间直接能把接口拖超时。所以超大对象，在Redis不是个好方案！在受限于业务上，只能放在本地。

引入自动Mock填充Java属性的工具

        <dependency>
            <groupId>com.github.jsonzou</groupId>
            <artifactId>jmockdata</artifactId>
            <version>4.3.0</version>
            <scope>compile</scope>
        </dependency>

测试20wJava对象占用内存

import com.github.jsonzou.jmockdata.JMockData;
import lombok.SneakyThrows;

import java.lang.management.ManagementFactory;
import java.lang.management.MemoryMXBean;
import java.lang.management.MemoryUsage;
import java.util.ArrayList;

public class MemoryUsageExample {
    @SneakyThrows
    public static void main(String[] args) {
        MemoryMXBean memoryBean = ManagementFactory.getMemoryMXBean();
        MemoryUsage memoryUsage = memoryBean.getHeapMemoryUsage();
        ArrayList<AHItem> ahItems = new ArrayList<>();
        long beforeMemory = memoryUsage.getUsed();

        // 执行一些操作，让对象占用内存
        for (int i = 0; i < 200000; i++) {
            ahItems.add(JMockData.mock(AHItem.class));
        }
        long afterMemory = memoryBean.getHeapMemoryUsage().getUsed();
        long objectMemoryUsage = afterMemory - beforeMemory;
        double objectMemoryUsageInMB = (double) objectMemoryUsage / (1024 * 1024);
        System.out.println("该对象占用的内存为: " + objectMemoryUsageInMB + " MB");
    }
}

输出

该对象占用的内存为: 101.98395538330078 MB