jvm溢出实现

男娘i 2021-10-01 10:14 196阅读 0赞

java堆溢出

public class HeapOOM {
        static class OOMObject{
    
        }
    
        public static void main(String[] args) {
            List<OOMObject> list=new ArrayList<OOMObject>();
            while (true){
                list.add(new OOMObject());
            }
        }
    
    }

设置参数

-Xms20m -Xmx20m -XX:+HeapDumpOnOutOfMemoryError
    //-XX:+HeapDumpOnOutOfMemoryError 内存溢出时dump出当前内存转储快照以便分析

抛出异常

java.lang.OutOfMemoryError: Java heap space
    Dumping heap to java_pid16032.hprof ...
    Heap dump file created [28242928 bytes in 0.083 secs]
    Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
        at java.util.Arrays.copyOf(Arrays.java:3210)
        at java.util.Arrays.copyOf(Arrays.java:3181)
        at java.util.ArrayList.grow(ArrayList.java:261)
        at java.util.ArrayList.ensureExplicitCapacity(ArrayList.java:235)
        at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:227)
        at java.util.ArrayList.add(ArrayList.java:458)
        at test1227.HeapOOM.main(HeapOOM.java:14)

--------------------

虚拟机和本地方法栈溢出

栈溢出 -Xss设置栈容量大小  
单线程只抛出stackoverflow异常

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

设置参数-Xss128k 减少栈内存容量

stack length990
    Exception in thread "main" java.lang.StackOverflowError
        at test1227.JavaVMStackSOF.stackLeak(JavaVMStackSOF.java:6)
        at test1227.JavaVMStackSOF.stackLeak(JavaVMStackSOF.java:7)
        at test1227.JavaVMStackSOF.stackLeak(JavaVMStackSOF.java:7)
        at test1227.JavaVMStackSOF.stackLeak(JavaVMStackSOF.java:7)

--------------------

创建线程导致内存溢出异常  
（不要在windows上执行这段代码）

public class JavaVMStackOOM {
        private void 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();
        }
    }

--------------------

方法区

/**
     * @description: VM Args:-XX:PermSize=10M -XX:MaxPermSize=10M jdk1.6及之前版本
     * @author: icecrea
     * @create: 2018-10-17 17:22
     **/
    public class RuntimeConstantPoolOOM {
        public static void main(String[] args) {
            //使用list保持常量池引用，避免full gc回收常量池行为
            List<String> list=new ArrayList<>();
            //10MB的PermSize在integer范围足够产生OOM
            int i=0;
            while(true){
                list.add(String.valueOf(i++).intern());
            }
        }
    }

使用Cglib使方法区出现内存溢出异常  
在动态生成大量class的应用中，注意类的回收状况。这类场景除cglib字节码增强和动态语言外，还有大量jsp或动态产生jsp文件的应用

/**
     * @description:  VM Args:-XX:PermSize=10M -XX:MaxPermSize=10M
     * @author: icecrea
     * @create: 2018-10-17 17:47
     **/
    public class JavaMethodAreaOOM {
        public static void main(final String[] args) {
            while (true){
                Enhancer enhancer=new Enhancer();
                enhancer.setSuperclass(HeapOOM.OOMObject.class);
                enhancer.setUseCache(false);
                enhancer.setCallback(new MethodInterceptor() {
                    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
                        return methodProxy.invokeSuper(o,args);
                    }
                });
                enhancer.create();
            }
        }
    
        static class OOMObject{
    
        }
    }

--------------------

本机直接内存溢出

/**
     * @description: -Xmx20M -XX:MaxDirectMemorySize=10M
     * @author: icecrea
     * @create: 2018-10-17 17:57
     **/
    public class DirectMemoryOOM {
        private static final int _1MB=1024*1024;
    
        public static void main(String[] args) throws IllegalAccessException {
            Field unsafeField= Unsafe.class.getDeclaredFields()[0];
            unsafeField.setAccessible(true);
            Unsafe unsafe=(Unsafe)unsafeField.get(null);
            while(true){
                unsafe.allocateMemory(_1MB);
            }
        }
    }