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项目拓展-Jol分析本地对象or缓存的内存占用

news 来源：原创 2025/6/15 5:41:34

Jol可在开发过程中对数据两极进行评估判断是否可以使用本地缓存

依赖

<dependency><groupId>org.openjdk.jol</groupId><artifactId>jol-core</artifactId><version>0.16</version>
</dependency>

测试类

@Test
void test4() {List<IpBlacklistVO> ipBlacklistVOS = ipBlacklistDao.queryAllIp();log.info("数据:{}", ipBlacklistVOS);log.info("单个IpBlacklistVO内存布局:\n{}",ClassLayout.parseClass(IpBlacklistVO.class).toPrintable());// 分析整个列表内存占用log.info("列表总内存占用: {} bytes",GraphLayout.parseInstance(ipBlacklistVOS).totalSize());// 可选: 查看详细内存分布log.info("详细内存分布:\n{}",GraphLayout.parseInstance(ipBlacklistVOS).toFootprint());
}

输出

单个占用内存

[2025-05-07 12:18:33,260][INFO ][main] 单个IpBlacklistVO内存布局:
net.lab1024.sa.admin.module.phabusiness.ipblacklist.domain.vo.IpBlacklistVO object internals:
OFF  SZ               TYPE DESCRIPTION               VALUE0   8                    (object header: mark)     N/A8   4                    (object header: class)    N/A12   4   java.lang.String IpBlacklistVO.ip          N/A
Instance size: 16 bytes
Space losses: 0 bytes internal + 0 bytes external = 0 bytes total

列表占用内存

[2025-05-07 12:18:33,330][INFO ][main] 列表总内存占用: 267472 bytes (TestDelete.java:89)

内存详细分布

[2025-05-07 12:18:33,398][INFO ][main] 详细内存分布:
java.util.ArrayList@1343b038d footprint:COUNT       AVG       SUM   DESCRIPTION3483        32    111456   [B1     16672     16672   [Ljava.lang.Object;3483        24     83592   java.lang.String1        24        24   java.util.ArrayList3483        16     55728   net.lab1024.sa.admin.module.phabusiness.ipblacklist.domain.vo.IpBlacklistVO10451              267472   (total)