JavaJVM_OutofMemory

liudongdong1 收录于 Categories Framework

2021-05-04 约 382 字预计阅读 1 分钟 - 次阅读

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OutOfMemory异常原因：根据报错信息确定出是那个区域发生OutOfMemory异常，然后分析是内存泄露还是内存溢出。

内存泄漏：与GC Roots相关联并导致GC无法自动回收。

内存溢出：众多对象确实还必须活着，导致大量内存被占用而无法GC，当超出限制内存最大值时就抛出OutOfMemory异常。

.1. 堆溢出

import java.util.ArrayList;
import java.util.List;
public class HeapOut{
    static class OOMObjet{}
    public static void main(String[] args){
        List<OOMObjet> list=new ArrayList<OOMObjet>();
        while(true){
            list.add(new OOMObjet());
        }
    }
}

Exception in thread “main” java.lang.OutOfMemoryError: Java heap space at HeapOut.main(HeapOut.java:9)

CPU 和内存飙满了。

.2. 虚拟栈&本地方法溢出

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

public class HeapOut{
    private int stackLength=1;
    public void stackLeak(){
        stackLength++;
        stackLeak();
    }
    public static void main(String[] args) throws Throwable{
        HeapOut oom=new HeapOut();
        try{
            oom.stackLeak();
        }catch (Throwable e){
            System.out.println("stack Length:"+oom.stackLength);
            throw e;
        }
    }
}

操作系统给内个进程内存是有限的。

Exception in thread “main” java.lang.StackOverflowError at HeapOut.stackLeak(HeapOut.java:8) at HeapOut.stackLeak(HeapOut.java:8) at HeapOut.stackLeak(HeapOut.java:8) at HeapOut.stackLeak(HeapOut.java:8)

.3. 创建线程导致内存溢出

public class JavaVMStackOOM{
    private vodi dontStop(){
        while(true){ 
        }
    }
    public void stackLeakByThread(){
        while(true){
            Thread thread=new Thread(new Runnable(){
                @Override 
                public void run(){
                    dontStop();
                }
            });
            thread.start()
        }
    }
    public static void main(String[] args){
        JavaVMStackOOM oom=new JavaVMStackOOM();
        oom.stackLeakByThread();
    }
}

会导致电脑死机，Unable to create new native thread.

.4. 方法区&运行常量池溢出

public class RuntimeConstantPoolOOM{
    public static void main(String[] args){
        List<String>list=new ArrayList<String>();
        int i=0;
        while(true){
            list.add(String.valueOf(i++).intern());
        }
    }
}

java.lang.OutOfMemoryError: PerGen space;