1.概述
转载：基于JavaAgent的全链路监控四《JVM内存与GC信息》
2.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。
2.1 JvmStack
package com.javaagent.bytebuddy.demo;
import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.ManagementFactory;
import java.lang.management.MemoryMXBean;
import java.lang.management.MemoryUsage;
import java.util.Arrays;
import java.util.List;
/**
* 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 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);
}
}
}
2.2 MyAgent
import java.lang.instrument.Instrumentation;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
/**
* 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);
}
}
2.3 测试类
package com.javaagent.bytebuddy.demo;
import java.util.LinkedList;
import java.util.List;
/**
* -javaagent:/Users/lcc/IdeaProjects/lcc_work/test-byte-buddy/byte-buddy-v1x-javaagent-demo3/target/byte-buddy-v1x-javaagent-demo3-1.0-SNAPSHOT.jar=testsa
*
*/
public class JvmStackTest {
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");
}
}
}
MANIFEST.MF 文件如下
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifestEntries>
<addClasspath>true</addClasspath>
<!-- <Premain-Class>com.javaagent.bytebuddy.MyPreMainAgent</Premain-Class>-->
<Premain-Class>com.javaagent.bytebuddy.demo.MyAgent</Premain-Class>
<addDefaultImplementationEntries>true</addDefaultImplementationEntries>
<addDefaultSpecificationEntries>true</addDefaultSpecificationEntries>
<Can-Redefine-Classes>true</Can-Redefine-Classes>
<Can-Retransform-Classes>true</Can-Retransform-Classes>
</manifestEntries>
</archive>
</configuration>
</plugin>
2.4 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