案例简述
除了监控java方法的执行耗时，我们还需要获取应用实例的jvm内存与gc信息，以实时把控我们的服务器性能是否在安全范围。监控jvm内存与gc信息是非常重要的，尤其是在大促以及微博火热爆点的时候，我们需要根据监控信息进行扩容，以保证系统稳定。
环境准备
1、IntelliJ IDEA Community Edition
2、jdk1.8.0_45 64位
配置信息
（路径相关修改为自己的）
1、配置位置：Run/Debug Configurations -> VM options
2、配置内容：-javaagent:E:\itstack\GIT\itstack.org\itstack-demo-agent\itstack-demo-agent-04\target\itstack-demo-agent-04-1.0.0-SNAPSHOT.jar=testargs
代码示例
itstack-demo-agent-04 ├── pom.xml └── src ├── main │ ├── java │ │ └── org.itstack.demo.agent │ │ ├── JvmStack.java │ │ └── MyAgent.java │ └── resources │ └── META-INF │ └── MANIFEST.MF └── test └── java └── org.itstack.demo.test └── ApiTest.java
JvmStack.java
/** * 博客：http://itstack.org * 论坛：http://bugstack.cn * 公众号：bugstack虫洞栈 ｛获取学习源码｝ * create by fuzhengwei on 2019 */ class JvmStack { private static final long MB = 1048576L; static void printMemoryInfo() { MemoryMXBean memory = ManagementFactory.getMemoryMXBean(); MemoryUsage headMemory = memory.getHeapMemoryUsage(); String info = String.format("\ninit: %s\t max: %s\t used: %s\t committed: %s\t use rate: %s\n", headMemory.getInit() / MB + "MB", headMemory.getMax() / MB + "MB", headMemory.getUsed() / MB + "MB", headMemory.getCommitted() / MB + "MB", headMemory.getUsed() * 100 / headMemory.getCommitted() + "%" ); System.out.print(info); MemoryUsage nonheadMemory = memory.getNonHeapMemoryUsage(); info = String.format("init: %s\t max: %s\t used: %s\t committed: %s\t use rate: %s\n", nonheadMemory.getInit() / MB + "MB", nonheadMemory.getMax() / MB + "MB", nonheadMemory.getUsed() / MB + "MB", nonheadMemory.getCommitted() / MB + "MB", nonheadMemory.getUsed() * 100 / nonheadMemory.getCommitted() + "%" ); System.out.println(info); } static void printGCInfo() { List<GarbageCollectorMXBean> garbages = ManagementFactory.getGarbageCollectorMXBeans(); for (GarbageCollectorMXBean garbage : garbages) { String info = String.format("name: %s\t count:%s\t took:%s\t pool name:%s", garbage.getName(), garbage.getCollectionCount(), garbage.getCollectionTime(), Arrays.deepToString(garbage.getMemoryPoolNames())); System.out.println(info); } } }
MyAgent.java
/** * 博客：http://itstack.org * 论坛：http://bugstack.cn * 公众号：bugstack虫洞栈 ｛获取学习源码｝ * create by fuzhengwei on 2019 */ public class MyAgent { public static void premain(String agentArgs, Instrumentation inst) { System.out.println("this is my agent：" + agentArgs); Executors.newScheduledThreadPool(1).scheduleAtFixedRate(new Runnable() { public void run() { JvmStack.printMemoryInfo(); JvmStack.printGCInfo(); System.out.println("==================================================================================================="); } }, 0, 5000, TimeUnit.MILLISECONDS); } }
MANIFEST.MF
Manifest-Version: 1.0 Premain-Class: org.itstack.demo.agent.MyAgent Can-Redefine-Classes: true
ApiTest.java
/** * 博客：http://itstack.org * 论坛：http://bugstack.cn * 公众号：bugstack虫洞栈 ｛获取学习源码｝ * create by fuzhengwei on 2019 * -javaagent:E:\itstack\GIT\itstack.org\itstack-demo-agent\itstack-demo-agent-04\target\itstack-demo-agent-04-1.0.0-SNAPSHOT.jar=testargs */ public class ApiTest { public static void main(String[] args) { while (true) { List<Object> list = new LinkedList<>(); list.add("嗨！JavaAgent"); list.add("嗨！JavaAgent"); list.add("嗨！JavaAgent"); } } }
测试结果
this is my agent：testargs init: 192MB max: 2708MB used: 5MB committed: 184MB use rate: 3% init: 2MB max: 0MB used: 5MB committed: 7MB use rate: 75% name: PS Scavenge count:1 took:2 pool name:[PS Eden Space, PS Survivor Space] name: PS MarkSweep count:0 took:0 pool name:[PS Eden Space, PS Survivor Space, PS Old Gen] =================================================================================================== init: 192MB max: 2708MB used: 249MB committed: 624MB use rate: 39% init: 2MB max: 0MB used: 6MB committed: 7MB use rate: 78% name: PS Scavenge count:32 took:98 pool name:[PS Eden Space, PS Survivor Space] name: PS MarkSweep count:0 took:0 pool name:[PS Eden Space, PS Survivor Space, PS Old Gen] =================================================================================================== Process finished with exit code -1