JVM-周阳讲解

待我称王封你为后i 2023-06-20 06:54 2阅读 0赞

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1.  `package com.shi.jvm;`
2.   
3.  `public class StackTest {`
4.   
5.  `/**`
6.  `* 递归调用`
7.  `*/`
8.  `public static void add() {`
9.  `add();`
10. `}`
11.  
12. `/**`
13. `* 栈满了异常`
14. `* Exception in thread "main" java.lang.StackOverflowError`
15. `* @param args`
16. `*/`
17. `public static void main(String[] args) {`
18. `add();`
19. `}`
20.  
21. `}`

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1.  `package com.shi.jvm;`
2.   
3.  `public class HeapTest {`
4.   
5.  `public static void main(String[] args) {`
6.   
7.  `/**`
8.  `* 堆内存异常`
9.  `* 输出结果：当前最大可用内存多少M : 1724`
10. `* Exception in thread "main" java.lang.OutOfMemoryError: Java heap space`
11. `* at com.shi.jvm.HeapTest.main(HeapTest.java:8)`
12. `*/`
13. `System.out.println("当前最大可用内存多少M : "+Runtime.getRuntime().maxMemory()/1024/1024);`
14. `//创建一个大对象`
15. `byte[] b = new byte[1*1024*1024*1725];`
16. `System.out.println("大对象创建成功");`
17. `}`
18.  
19. `}`

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1.  `package com.shi.jvm;`
2.   
3.  `import java.util.Random;`
4.  `/**`
5.  `* -Xms1024m -Xmx1024m -XX:+PrintGCDetails`
6.  `堆初始化内存，堆最大内存 打印出堆GC回收信息`
7.  `* @author shiye`
8.  `*`
9.  `*/`
10. `public class HeapSpaceTest {`
11.  
12.  
13. `public static void main(String[] args) {`
14.  
15. `/**`
16. `* 输出： MAX_MEMERY = 1808269312（字节）1724.5MB`
17. `TOTAL_MEMERY = 122683392（字节）117.0MB`
18. `* @param args`
19. `*/`
20. `// long maxMemory = Runtime.getRuntime().maxMemory();//返回Java虚拟机试图使用的最大内存量`
21. `// long totalMemory = Runtime.getRuntime().totalMemory();//返回当前使用的java虚拟机的内存总量`
22. `// System.out.println("MAX_MEMERY = " + maxMemory +"（字节）" + (maxMemory/(double)1024/1024) + "MB");`
23. `// System.out.println("TOTAL_MEMERY = " + totalMemory +"（字节）" + (totalMemory/(double)1024/1024) + "MB");`
24.  
25.  
26. `//-Xms8m -Xmx8m -XX:+PrintGCDetails`
27. `String str = "www.shiye";`
28. `while(true) {`
29. `str += str + new Random().nextInt(9999);`
30. `}`
31. `/**`
32. `* 结果： Exception in thread "main" java.lang.OutOfMemoryError: Java heap space`
33. `*/`
34. `}`
35. `}`

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