实战 OutOfMemoryError异常

青旅半醒 2022-05-14 13:59 147阅读 0赞

# 1、java堆溢出 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70][]

代码如下

import java.util.ArrayList;
    import java.util.List;
    
    /**
     * Vm args:-Xms20M -Xmx20M -XX:+HeapDumpOnOutOfMemoryError
     * 堆的最小值参数-Xms，堆的最大值参数-Xmx
     * -XX:+HeapDumpOnOutOfMemoryError表示让虚拟机在出现内存异常时Dump出当前的内存堆转储快照
     * -XX:HeapDumpPath:为快照文件位置
     * Java 堆内存溢出测试，深入理解java虚拟机 p51
     */
    //-Xms20m -Xmx20m -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=C:/
    public class HeapOOM {
    
        static class OOMObject{}
    
        //psvm
        public static void main(String[] args) {
    
            List<OOMObject> list = new ArrayList<OOMObject>();
            while (true){
                list.add(new OOMObject());
            }
        }
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 1][]

运行

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 2][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 3][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 4][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 5][]

我们用Memory Analyzer 打开 dump出来的堆转储快照

官网：http://www.eclipse.org/mat/downloads.php 下载

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 6][]

打开![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 7][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 8][]

具体分析就不说了

# 2、java虚拟机栈和本地方法栈溢出 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 9][]

/**
     * VM args:-Xss128k
     * -Xss128k 减小栈内存至128k
     */
    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;
            }
     }
    }

运行

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 10][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 11][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 12][]

/\*\*  
 \* VM args:-Xss2M  
 \* 该程序执行容易死机，我的电脑运行死机两次  
 \*  
 \*/  
public class JavaVMStatckOOM\{  
    public void dontStop()\{  
        while(true)\{      
        \}  
    \}  
    public void stackLeakByThread()\{  
        while(true)\{  
            Thread t = new Thread(new Runnable() \{  
                @Override  
                public void run() \{  
                    dontStop();  
                \}  
            \});  
            t.start();  
        \}  
    \}  
    public static void main(String\[\] args) \{  
        JavaVMStatckOOM sofm = new JavaVMStatckOOM();  
        sofm.stackLeakByThread();  
    \}  
\}

书上的运行结果如下

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 13][]

3、方法区和运行时常量池溢出

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 14][]

/\*\*  
 \* VM args:-XX:PermSize=10M -XX:MaxPermSize=10M  
 \* PermSize 方法区大小  
 \*/  
public class RuntimeContantPoolOOM\{  
    public static void main(String\[\] args) \{  
        //使用List保存对常量池字符串的应用，避免Full GC回收常量池的行为  
        List<String> list = new ArrayList<String>();  
        //10M的PermSize在int的范围足够产生OutOfMemoryError  
        int i = 0;  
        while(true)\{  
            list.add(String.valueOf(i++).intern());  
        \}  
    \}  
\}  
运行结果（JDK1.6及之前的运行结果），  
Exception in thread “main” java.lang.OutOfMemoryError: PermGen space  
在jdk6及之前，常量池分配在永久代内，通过-XX:PermSize10M -XX:MaxPermSize=10M限制其大小，而JDK1.7后就不会出现相同的结果，while循环将一直进行下去。。。。。。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 15][]

public static void main(String[] args) {
            String str1 = new StringBuilder("计算机").append("软件").toString();
            System.out.println(str1.intern()==str1);
            String str2 = new StringBuilder("ja").append("va").toString();
            System.out.println(str2.intern() == str2);
            String str3 = new StringBuilder("goo").append("gle").toString();
            System.out.println(str3.intern() == str3);
    
        }

结果如下

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 16][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 17][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 18][]

/\*\*  
 \* VM Args： -XX:PermSize=10M -XX:MaxPermSize=10M  
 \*/  
public class JavaMethodAreaOOM \{  
   
    public static void main(String\[\] args) \{  
        while (true) \{  
            Enhancer enhancer = new Enhancer();  
            enhancer.setSuperclass(OOMObject.class);  
            enhancer.setUseCache(false);  
            enhancer.setCallback(new MethodInterceptor() \{  
                @Override  
                public Object intercept(Object obj, Method method, Object\[\] arg, MethodProxy proxy) throws Throwable \{  
                    // TODO Auto-generated method stub  
                    return proxy.invokeSuper(obj, arg);  
                \}  
            \});  
            enhancer.create();  
        \}  
    \}  
    static class OOMObject \{  
   
    \}  
\}

运行结果：

Caused by: java.lang.OutOfMemoryError: PermGen space

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 19][]

# 4、本机直接内存溢出 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 20][]

/\*\*  
 \* VM Args：-Xmx20M -XX:MaxDirectMemorySize=10M  
 \*/  
public class DirectMemoryOOM \{  
    private static final int \_1MB = 1024 \* 1024;  
    public static void main(String\[\] args) throws Exception \{  
        Field unsafeField = Unsafe.class.getDeclaredFields()\[0\];  
        unsafeField.setAccessible(true);  
        Unsafe unsafe = (Unsafe) unsafeField.get(null);  
        while (true) \{  
            unsafe.allocateMemory(\_1MB);  
        \}  
    \}  
\}  
运行结果：  
Exception in thread "main" java.lang.OutOfMemoryError   
    at sun.misc.Unsafe.allocateMemory(Native Method)   
    at baby.oom.DirectMemoryOOM.main(DirectMemoryOOM.java:20)   
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3VvdGFpbA_size_27_color_FFFFFF_t_70 21][]

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实战 OutOfMemoryError异常

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