jvm cpu异常分析（VisualVM）

青旅半醒 2023-02-28 08:53 46阅读 0赞

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### jvm cpu异常分析（VisualVm） ###

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**示例**

**Test2.java：死锁测试**

class MyThread implements Runnable{
    
        private final boolean flag;
    
        private final Object lock="lock";
        private final Object lock2="lock2";
    
        public MyThread(boolean flag){
            this.flag=flag;
        }
    
        @Override
        public void run() {
            if (flag){
                synchronized (lock){
                    try {
                        System.out.println(Thread.currentThread().getId()+" 获取对象：lock");
                        Thread.sleep(2000);
                    }catch (Exception e){
                        System.out.println(e.getMessage());
                    }
    
                    synchronized (lock2){
                        System.out.println(Thread.currentThread().getId()+" 获取对象：lock2");
                    }
                }
            }else {
                synchronized (lock2){
                    try {
                        System.out.println(Thread.currentThread().getId()+" 获取对象：lock2");
                        Thread.sleep(2000);
                    }catch (Exception e){
                        System.out.println(e.getMessage());
                    }
    
                    synchronized (lock){
                        System.out.println(Thread.currentThread().getId()+" 获取对象：lock");
                    }
                }
            }
        }
    }
    
    public class Test2 {
    
        public static void main(String[] args){
            Thread t1=new Thread(new MyThread(true));
            Thread t2=new Thread(new MyThread(false));
    
            t1.start();
            t2.start();
        }
    }

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**控制台输出**

16 获取对象：lock2
    15 获取对象：lock

**控制台输出后，长时间停止输出**

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**相关操作**

**monitor**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkzMTYyNQ_size_16_color_FFFFFF_t_70][]

**java应用称序占系统cpu时间并不大**

**sampler ==> cpu**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkzMTYyNQ_size_16_color_FFFFFF_t_70 1][]

**java程序中线程Thread-0、Thread-1 cpu使用率均为100%**

**Threads**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkzMTYyNQ_size_16_color_FFFFFF_t_70 2][]

**检测到出现了死锁**

**Threads ==> Thread Dump：生成线程快照**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkzMTYyNQ_size_16_color_FFFFFF_t_70 3][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkzMTYyNQ_size_16_color_FFFFFF_t_70 4][]

**死锁出现在com.example.demo.jvm.MyThread.run方法中**

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