Jconsole

 JConsole (Java Monitoring and Management Console）是一种基于 JMX 的可视化监视、管理工具，它管理部分的功能是针对 JMXMBean 进行管理，由于 MBean 可以使用代码、中间件服务器的管理控制台或者所有符合 JMX 规范的软件进行访问。
 jconsole集成了线程与内存的可视化展示。

Jconsole连接方式

• 本地连接：通过JDK/bin目录下的“jconsole.exe”启动JConsole 后，将自动搜索出本机运行的所有虚拟机进程，不需要用户自己再使用 jps 来查询了。
• 远程连接

# 生成项目jar
mvn install 

# scp将jar包进行远程复制
sudo  scp  /Users/daniel/Desktop/jvm-demo-0.0.1-SNAPSHOT.jar  root@172.16.244.151:/usr/local

# 将jar包启动  
	#nohup代表以守护线程的方式启动
	# -Dcom.sun.management.jmxremote.port 开启远程访问JXM端口
nohup java -Xms800m -Xmx800m -XX:PermSize=256m -XX:MaxPermSize=512m -XX:MaxNewSize=512m -Dcom.sun.management.jmxremote.port=9999 -Djava.rmi.server.hostname=192.168.31.220 -Dcom.sun.management.jmxremote.ssl=false 
-Dcom.sun.management.jmxremote.authenticate=false -jar /test/jvm-demo-0.0.1-SNAPSHOT.jar &

# 远程连接
	远程进程： 192.168.31.220:9999
	用户名:root	密码：123

Jconsole内存监控验证

模拟内存增长示例

public class JconsoleMemory {
    public byte[] b1 = new byte[1024 * 512];

    public static void main(String[] args) throws InterruptedException {
        System.out.println("main thread start!");
        Thread.sleep(10000); //休眠10秒
        allocate(10000);
    }

    private static void allocate(int n){
        List<JconsoleMemory> jconsoleMemoryList = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            try {
                Thread.sleep(100);
            } catch (InterruptedException e){
                e.printStackTrace();
            }
            jconsoleMemoryList.add(new JconsoleMemory());
        }
    }
}

Jconsole线程验证

@SpringBootApplication
@EnableAutoConfiguration
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

	private static  Object lock1 = new Object();
	private static  Object lock2 = new Object();

	class WaitCondition{
		boolean isOpen = false;
		public  void setOpen(){
			isOpen = true;
		}
	}

	WaitCondition waitCondition = new WaitCondition();

	/**
	 * 在springboot项目启动的时候所执行的方法
	 * 在bean加载完但用户线程进来之前执行的方法
	 */
	@PostConstruct
	public void deadLock(){
		new Thread(()->{
			synchronized (lock1){
				try {
					System.out.println(Thread.currentThread().getName()+"得到Lock1");
					Thread.sleep(3000L);
				}catch (Exception e){
					e.printStackTrace();
				}
				synchronized (lock2){
					System.out.println(Thread.currentThread().getName()+"得到Lock2");
				}
			}
		},"线程1").start();


		new Thread(()->{
			synchronized (lock2){
				try {
					System.out.println(Thread.currentThread().getName()+"得到Lock2");
					Thread.sleep(3000L);
				}catch (Exception e){
					e.printStackTrace();
				}
				synchronized (lock1){
					System.out.println(Thread.currentThread().getName()+"得到Lock1");
				}
			}
		},"线程2").start();

		new Thread(()->{
			synchronized (waitCondition){
				while (!waitCondition.isOpen){
					try {
						waitCondition.wait();
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				}
			}
		},"线程3").start();

		new Thread(()->{
			synchronized (waitCondition){
				while (!waitCondition.isOpen){
					try {
						waitCondition.wait(1000000);
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
				}
			}
		},"线程4").start();
	}
}

VisualVM

 VisualVM是一个集成命令行JDK工具和轻量级分析功能的可视化工具。

VisualVM整合IDEA

# 安装插件
	搜索visualvm

# 点击配置VisualVM executable执行路径
	setting搜索visualvm
	F:/Development/JDK1.8/bin/jvisualvm.exe	

线程dump

"线程4" #34 prio=5 os_prio=0 tid=0x000000001f26d800 nid=0x3e9c in Object.wait() [0x00000000250cf000]

   java.lang.Thread.State: TIMED_WAITING (on object monitor)

	at java.lang.Object.wait(Native Method)
	- waiting on <0x0000000772319a10> (a com.xdclass.jvm.DemoApplication$WaitCondition)
	at com.xdclass.jvm.DemoApplication.lambda$deadLock$3(DemoApplication.java:83)
	- locked <0x0000000772319a10> (a com.xdclass.jvm.DemoApplication$WaitCondition)
	at com.xdclass.jvm.DemoApplication$$Lambda$299/1687627235.run(Unknown Source)
	at java.lang.Thread.run(Thread.java:745)

   Locked ownable synchronizers:
	- None

"线程3" #33 prio=5 os_prio=0 tid=0x0000000023996800 nid=0x9c in Object.wait() [0x0000000024fcf000]
   java.lang.Thread.State: WAITING (on object monitor)
	at java.lang.Object.wait(Native Method)
	- waiting on <0x0000000772319a10> (a com.xdclass.jvm.DemoApplication$WaitCondition)
	at java.lang.Object.wait(Object.java:502)
	at com.xdclass.jvm.DemoApplication.lambda$deadLock$2(DemoApplication.java:70)
	- locked <0x0000000772319a10> (a com.xdclass.jvm.DemoApplication$WaitCondition)
	at com.xdclass.jvm.DemoApplication$$Lambda$298/1971152916.run(Unknown Source)
	at java.lang.Thread.run(Thread.java:745)

   Locked ownable synchronizers:
	- None