【深入理解java虚拟机v3】代码清单2-4 、2-5虚拟机栈和本地方法栈测试

测试环境JDK1.8

-Xss 限制虚拟机栈的大小
-Xoss 限制本地方法栈大小

由于HotSpot虚拟机不区分虚拟机栈和本地方法栈，对于HotSpot来说，-Xoss参数虽然存在，但是没有实际效果。

虚拟机栈深度报错

代码清单2-4：

注意设置-Xss128k，限定了栈的上限，因此很快就报错

/**
 * VM Args：-Xss128k
 *
 * @author zzm
 */
public class JavaVMStackSOF_1 {
    
    

    private int stackLength = 1;

    public void stackLeak() {
    
    
        stackLength++;
        stackLeak();
    }

    public static void main(String[] args) throws Throwable {
    
    
        JavaVMStackSOF_1 oom = new JavaVMStackSOF_1();
        try {
    
    
            oom.stackLeak();
        } catch (Throwable e) {
    
    
            System.out.println("stack length:" + oom.stackLength);
            throw e;
        }
    }
}

执行结果，与书上相差不大：

stack length:2401
Exception in thread "main" java.lang.StackOverflowError
	at org.fenixsoft.jvm.chapter2.JavaVMStackSOF_1.stackLeak(JavaVMStackSOF_1.java:13)

栈申请内存不够报错

代码清单2-5：

定义了大量的本地变量，增大此方法帧中本地变量表的长度。本例中是100个long类型的变量，提前耗尽内存。

注意：没有限制栈的大小，不设置-Xss

/**
 * VM: JDK 1.0.2, Sun Classic VM
 *
 * @author zzm
 */
public class JavaVMStackSOF_3 {
    
    
    private static int stackLength = 0;

    public static void test() {
    
    
        long unused1, unused2, unused3, unused4, unused5, unused6, unused7, unused8, unused9, unused10, unused11, unused12, unused13, unused14, unused15, unused16, unused17, unused18, unused19, unused20, unused21, unused22, unused23, unused24, unused25, unused26, unused27, unused28, unused29, unused30, unused31, unused32, unused33, unused34, unused35, unused36, unused37, unused38, unused39, unused40, unused41, unused42, unused43, unused44, unused45, unused46, unused47, unused48, unused49, unused50, unused51, unused52, unused53, unused54, unused55, unused56, unused57, unused58, unused59, unused60, unused61, unused62, unused63, unused64, unused65, unused66, unused67, unused68, unused69, unused70, unused71, unused72, unused73, unused74, unused75, unused76, unused77, unused78, unused79, unused80, unused81, unused82, unused83, unused84, unused85, unused86, unused87, unused88, unused89, unused90, unused91, unused92, unused93, unused94, unused95, unused96, unused97, unused98, unused99, unused100;

        stackLength++;
        test();

        unused1 = unused2 = unused3 = unused4 = unused5 = unused6 = unused7 = unused8 = unused9 = unused10 = unused11 = unused12 = unused13 = unused14 = unused15 = unused16 = unused17 = unused18 = unused19 = unused20 = unused21 = unused22 = unused23 = unused24 = unused25 = unused26 = unused27 = unused28 = unused29 = unused30 = unused31 = unused32 = unused33 = unused34 = unused35 = unused36 = unused37 = unused38 = unused39 = unused40 = unused41 = unused42 = unused43 = unused44 = unused45 = unused46 = unused47 = unused48 = unused49 = unused50 = unused51 = unused52 = unused53 = unused54 = unused55 = unused56 = unused57 = unused58 = unused59 = unused60 = unused61 = unused62 = unused63 = unused64 = unused65 = unused66 = unused67 = unused68 = unused69 = unused70 = unused71 = unused72 = unused73 = unused74 = unused75 = unused76 = unused77 = unused78 = unused79 = unused80 = unused81 = unused82 = unused83 = unused84 = unused85 = unused86 = unused87 = unused88 = unused89 = unused90 = unused91 = unused92 = unused93 = unused94 = unused95 = unused96 = unused97 = unused98 = unused99 = unused100 = 0;
    }

    public static void main(String[] args) {
    
    
        try {
    
    
            test();
        } catch (Error e) {
    
    
            System.out.println("stack length:" + stackLength);
            throw e;
        }
    }
}

执行结果，栈深度仅为359就耗尽内存：

stack length:359
Exception in thread "main" java.lang.StackOverflowError
	at org.fenixsoft.jvm.chapter2.JavaVMStackSOF_3.test(JavaVMStackSOF_3.java:33)