使用Tomcat部署war包查看内存使用情况

前言：

        使用Tomcat部署多个war包，只有一个Java进程，使用常用方式只能看到整体占用内存情况。比如ps -aux 查看进程详情，或者使用jmap -heap查看JVM堆内存。

        如果想要看到每个war包对应的服务占用多少内存，提供如下两种简单的方式。

方式一：配置Actuator端点

1、在项目配置文件中添加

# 开放端点

management.endpoints.web.exposure.include=health,info,metrics

# 是否开启metrics端点，可以不配置

management.endpoint.metrics.enabled=true

2、用法

（1）查看全部指标

http://ip:port/actuator/metrics

{"names": ["jvm.buffer.count","jvm.buffer.memory.used","jvm.buffer.total.capacity","jvm.classes.loaded","jvm.classes.unloaded","jvm.gc.live.data.size","jvm.gc.max.data.size","jvm.gc.memory.allocated","jvm.gc.memory.promoted","jvm.gc.pause","jvm.memory.committed","jvm.memory.max","jvm.memory.used","jvm.threads.daemon","jvm.threads.live","jvm.threads.peak","jvm.threads.states","logback.events","process.cpu.usage","process.files.max","process.files.open","process.start.time","process.uptime","system.cpu.count","system.cpu.usage","system.load.average.1m","tomcat.cache.access","tomcat.cache.hit","tomcat.global.error","tomcat.global.received","tomcat.global.request","tomcat.global.request.max","tomcat.global.sent","tomcat.servlet.error","tomcat.servlet.request","tomcat.servlet.request.max","tomcat.threads.busy","tomcat.threads.config.max","tomcat.threads.current"]
}

常用内置指标端点

指标类别	端点路径示例	说明
JVM内存	/actuator/metrics/jvm.memory.used	JVM内存使用情况
HTTP请求	/actuator/metrics/http.server.requests	Web请求统计
系统CPU	/actuator/metrics/system.cpu.usage	CPU使用率
垃圾收集	/actuator/metrics/jvm.gc.pause	GC暂停时间
进程信息	/actuator/metrics/process.uptime	应用运行时间

（2）查看内存

http://ip:port/actuator/metrics/jvm.memory.used

说明：value是jvm全部占用内存，包括堆（PS Eden Space、PS Survivor Space、PS Old Gen）和非堆（Metaspace、Compressed Class Space、Code Cache）空间，单位bytes。转换成MB(/1024/1024)。

{"name": "jvm.memory.used","description": "The amount of used memory","baseUnit": "bytes","measurements": [{"statistic": "VALUE","value": 9897020928}],"availableTags": [{"tag": "area","values": ["heap","nonheap"]},{"tag": "id","values": ["Compressed Class Space","PS Survivor Space","PS Old Gen","Metaspace","PS Eden Space","Code Cache"]}]
}

（3）查看内存详细指标

格式：jvm.memory.used?tag=area:heap

比如，堆内存：http://ip:port/actuator/metrics/jvm.memory.used?tag=area:heap

{"name": "jvm.memory.used","description": "The amount of used memory","baseUnit": "bytes","measurements": [{"statistic": "VALUE","value": 8406602104}],"availableTags": [{"tag": "id","values": ["PS Eden Space","PS Survivor Space","PS Old Gen"]}]
}

非堆内存：http://ip:port/actuator/metrics/jvm.memory.used?tag=area:nonheap

{"name": "jvm.memory.used","description": "The amount of used memory","baseUnit": "bytes","measurements": [{"statistic": "VALUE","value": 1519950712}],"availableTags": [{"tag": "id","values": ["Metaspace","Compressed Class Space","Code Cache"]}]
}

方式二：通过代码获取

import java.lang.management.ManagementFactory;
import java.lang.management.MemoryMXBean;
import java.lang.management.MemoryPoolMXBean;
import java.lang.management.MemoryUsage;public class MemoryMonitor {public static void main(String[] args) {// 获取堆内存使用MemoryMXBean memoryMxBean = ManagementFactory.getMemoryMXBean();MemoryUsage heapUsage = memoryMxBean.getHeapMemoryUsage();System.out.println("Heap Memory Used: " + heapUsage.getUsed() / 1024 / 1024 + " MB");// 获取各内存池详情for (MemoryPoolMXBean pool : ManagementFactory.getMemoryPoolMXBeans()) {MemoryUsage usage = pool.getUsage();System.out.printf("Pool: %s, Used: %d MB%n", pool.getName(), usage.getUsed() / 1024 / 1024);}}
}

输出：

Memory Monitor:
Heap Memory Used: 7931 MB
Pool: Code Cache, Used: 152 MB

Pool: Metaspace, Used: 1149 MB

Pool: Compressed Class Space, Used: 144 MB

Pool: PS Eden Space, Used: 2060 MB

Pool: PS Survivor Space, Used: 140 MB

Pool: PS Old Gen, Used: 5730 MB

关键内存区域说明

内存区域	说明
G1 Eden Space	年轻代Eden区，新对象首先分配在这里
G1 Survivor Space	年轻代Survivor区，存放从Eden区GC后存活的对象
G1 Old Gen	老年代，存放长期存活的对象
Metaspace	存储类元数据(取代永久代)，不包含在堆内存中
Code Cache	JIT编译后的本地代码存储区域
Compressed Class Space	压缩指针使用的类空间