JDK性能分析与故障处理-命令行

一、命令演示
登录主机：21
docker ps -a | grep 'hub.ecs.com:6999/open_pro.*open-pro-apple2'
docker exec -it ID /bin/bash

jps

jinfo 1
jinfo 1 | grep 'sun.java.command' //程序参数 main方法入参
jinfo 1 | grep 'Command line' //虚拟机系统参数，全局参数

jstat -gc 1 3s 10
jstat -gcutil 1 3s 10

#简单看下后续有实例分析
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docker ps -a | grep 'test.com:6999/open_2k'
docker exec -it ID /bin/bash

jstack 1 > stack1.txt
cat stack1.txt | grep 'java.lang.Thread.State'
cat stack1.txt | grep 'java.lang.Thread.State'| wc -l
cat stack1.txt | grep 'java.lang.Thread.State'|sort| uniq
线程状态：https://docs.oracle.com/javase/8/docs/api/java/lang/Thread.State.html
New、Runnable(Runnable/Running)、Blocked(Blocked/WAITING/TIMED_WAITING)、Dead

#需要工具分析，肉眼不可读
jmap -dump:format=b,file=dump2019.dump 1

二、实例分析（代码见分割线下方）

1.BigObject
VM Options：-Xmx30M -Xms30M
1.1命令行观察内存变化
jstat -gcutil 1 1s 200

1.2visualVM观察

2.SupperBigObject
VM Options：-Xmx30M -Xms30M
1.1命令行观察内存变化
jstat -gcutil 1 1s 200
jstat -gc 1 1s 200

1.2visualVM观察

3.HighCPU（分析stack）

3.1 jstack或visualVM查看栈快照
jstack 1 > HighCPU.txt
本地方便则使用visualVM更方便
3.2 top命令
a."top"命令查找cpu高的进程pid
b."top -Hp pid" 查找cpu高的线程
(mac )
java -jar jvm-1.0-jar-with-dependencies.jar
9551-9584
jstack 9551 > HighCPU.txt
9584->0x2570
grep '0x2570' HighCPU.txt

4.OutOffMem（分析dump）
jmap或visualVM查看栈快照
jmap -dump:format=b,file=dump2019.dump pid

----分割线----以下是练习的代码---

package zero.desk.jdkcommand;

import java.util.ArrayList;
import java.util.List;

/**
 * @author Zero
 * @since 2019-09-21.
 * Description:
 * VM Options：-Xmx30M -Xms30M
 */
public class BigObject {
    public Object instance = null;
    private static final int ONE_MB = 1024 * 1024;

    private byte[] bigSize = new byte[2 * ONE_MB];

    public static void main(String[] args) throws InterruptedException {
        Thread.sleep(12000);
        for(int i=0;i<100;i++){
            Thread.sleep(1000);
            testGC();
        }
    }

    private static void testGC() {
        BigObject objA = new BigObject();
        BigObject objB = new BigObject();
        objA.instance = objB;
        objB.instance = objA;
//        System.gc();
    }
}

//----

package zero.desk.jdkcommand;

/**
 * @author Zero
 * @since 2019-09-21.
 * Description:
 */
public class HighCPU {
    public static void main(String[] args) {
        new Thread(() -> {
            double d = 2.3;
            while (true) {
                long i = 1;
                d = d * d;
                if (i % 100000 == 0) {
                    System.out.println(i);
                }
            }
        }).start();


        new Thread(() -> {
            long l = 1;
            while (true) {
                l++;
                if (l % 100 == 0) {
                    try {
                        Thread.sleep(100);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();

    }
}

//---

package zero.desk.jdkcommand;

import java.util.ArrayList;
import java.util.List;

/**
 * @author Zero
 * @since 2019-09-21.
 * Description:
 * VM Options：-Xmx50M -Xms50M
 */
public class OutOffMem {

    private static List<BigObject> GCRoot = new ArrayList<>();

    public static void main(String[] args) throws InterruptedException {
        Thread.sleep(12000);
        for(int i=0;i<100;i++){
            Thread.sleep(1000);
            testGC();
        }
    }

    private static void testGC() {
        BigObject objA = new BigObject();
        BigObject objB = new BigObject();
        objA.instance = objB;
        objB.instance = objA;
        //内存不会释放
        GCRoot.add(objA);
        GCRoot.add(objB);
        System.gc();
    }
}

//----

package zero.desk.jdkcommand;

/**
 * @author Zero
 * @since 2019-09-21.
 * Description:
 * VM Options：-Xmx30M -Xms30M
 * 超过survivor的直接进入eden
 * 超过年轻代的直接进入老年代
 */
public class SupperBigObject {
    public Object instance = null;
    private static final int ONE_MB = 1024 * 1024;

//    private byte[] bigSize = new byte[8 * ONE_MB];
    private byte[] bigSize = new byte[9 * ONE_MB];

    public static void main(String[] args) throws InterruptedException {
        Thread.sleep(12000);
        for(int i=0;i<100;i++){
            Thread.sleep(1000);
            testGC();
        }
    }

    private static void testGC() {
        SupperBigObject objA = new SupperBigObject();
        SupperBigObject objB = new SupperBigObject();
        objA.instance = objB;
        objB.instance = objA;
//        System.gc();
    }
}