搞定Hotspot-api

目的，搞这玩意儿，无非想学习下hotspot中的java对象体系。恩直接上代码吧。

做了一个工程：

待观察类：

package hotspot.api.test;

/**
 * hotspot 观察类
 * @author 
 *
 */
public class Wukong {
    public static int wk_static_i = 7777777;
    private int wk_instance_i;
    
    public Wukong(int wk_instance_i) {
        this.wk_instance_i = wk_instance_i;
    }
    public int getWk_instance_i() {
        return wk_instance_i;
    }
}

运行线程：

package hotspot.api.test;

import java.io.IOException;

public class WukongRun {
    
    public static void main(String args[]){
        new Wukong(8888);
        try {
            System.in.read();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

attach工具：

package hotspot.api.test;

import sun.jvm.hotspot.oops.HeapVisitor;
import sun.jvm.hotspot.oops.Klass;
import sun.jvm.hotspot.oops.ObjectHeap;
import sun.jvm.hotspot.oops.Oop;
import sun.jvm.hotspot.oops.OopPrinter;
import sun.jvm.hotspot.runtime.VM;

public class HotspotApiTest extends sun.jvm.hotspot.tools.Tool {

    public static void main(String args[]) {
        HotspotApiTest ht = new HotspotApiTest();
        ht.start(args);
        ht.stop();
    }

    @Override
    public void run() {
        VM vm = VM.getVM();
        final ObjectHeap objectHeap = vm.getObjectHeap();
        objectHeap.iterate(new HeapVisitor() {
            @Override
            public void prologue(long l) {
            }

            @Override
            public boolean doObj(Oop oop) {
                System.out.println("////////////////////////////////////////");
                System.out.println("OOP#" + oop);
                oop.iterate(new OopPrinter(System.out), true);
                System.out.println("////////////////////////////////////////");
                System.out.println("OOP.KLASS#" + oop.getKlass());
                oop.getKlass().iterate(new OopPrinter(System.out), true);
                System.out.println("////////////////////////////////////////");
                System.out.println("OOP.KLASS.MIRROR#" + oop.getKlass().getJavaMirror());
                oop.getKlass().getJavaMirror().iterate(new OopPrinter(System.out), true);
                System.out.println("////////////////////////////////////////");
                System.out.println("OOP.KLASS.KLASS#" + oop.getKlass().getKlass());
                oop.getKlass().getKlass().iterate(new OopPrinter(System.out), true);
                System.out.println("////////////////////////////////////////");
                System.out.println("OOP.KLASS.KLASS.KLASS#" + oop.getKlass().getKlass().getKlass());
                oop.getKlass().getKlass().getKlass().iterate(new OopPrinter(System.out), true);
                System.out.println("////////////////////////////////////////");
                System.out.println("OOP.KLASS.KLASS.KLASS.KLASS#" + oop.getKlass().getKlass().getKlass().getKlass());
                oop.getKlass().getKlass().getKlass().getKlass().iterate(new OopPrinter(System.out), true);
                return false;
            }

            @Override
            public void epilogue() {
            }

        }, new ObjectHeap.ObjectFilter() {
            @Override
            public boolean canInclude(Oop oop) {
                Klass klass = oop.getKlass();
                return klass.getName() != null && "hotspot/api/test/Wukong".equals(klass.getName().asString());
            }
        });
    }

}

首先把代码编译一下：

javac -cp /home/software/jdk1.7.0_80/lib/sa-jdi.jar -d bin -sourcepath src src/main/java/hotspot/api/test/*.java

这里边要用到sa-jdi.jar这个包；eclipse下需要专门在jre配置里导入这个包才能正常编译。

然后先到bin目录下执行：

java hotspot.api.test.WukongRun

新开窗口，执行：

java -classpath /home/software/jdk1.7.0_80/lib/sa-jdi.jar: hotspot.api.test.HotspotApiTest 3475

3475就是上边WukongRun的线程id。

输出结果：

////////////////////////////////////////
OOP#sun.jvm.hotspot.oops.Instance@ef44eb00
Oop for hotspot/api/test/Wukong @ 0x00000000ef44eb00 (object size = 16)
 - _mark:     {0} :1
 - _metadata._compressed_klass:     {8} :InstanceKlass for hotspot/api/test/Wukong @ 0x00000000fb062e60
 - wk_instance_i:     {12} :8888

////////////////////////////////////////
OOP.KLASS#sun.jvm.hotspot.oops.InstanceKlass@fb062e60
InstanceKlass for hotspot/api/test/Wukong @ 0x00000000fb062e60 (object size = 568)
 - _mark:     {0} :1
 - _metadata._compressed_klass:     {8} :InstanceKlassKlass @ 0x00000000fae00270
 - _java_mirror:     {120} :Oop for java/lang/Class @ 0x00000000ef44eaa0
 - _super:     {128} :InstanceKlass for java/lang/Object @ 0x00000000fae02bb0
 - _layout_helper:     {24} :16
 - _access_flags:     {156} :33
 - _subklass:     {136} :null
 - _next_sibling:     {144} :InstanceKlass for java/lang/Void @ 0x00000000fb0627c0
 - _alloc_count:     {160} :0
 - _array_klasses:     {200} :null
 - _methods:     {208} :ObjArray @ 0x00000000fb062bd0
 - _method_ordering:     {216} :[I @ 0x00000000fae01c30
 - _local_interfaces:     {224} :ObjArray @ 0x00000000fae01c40
 - _transitive_interfaces:     {232} :ObjArray @ 0x00000000fae01c40
 - _fields:     {240} :[S @ 0x00000000fb062ba8
 - _constants:     {248} :ConstantPool for hotspot/api/test/Wukong @ 0x00000000fb062a70
 - _class_loader:     {256} :Oop for sun/misc/Launcher$AppClassLoader @ 0x00000000ef442c58
 - _protection_domain:     {264} :Oop for java/security/ProtectionDomain @ 0x00000000ef44c568
 - _signers:     {272} :null
 - _inner_classes:     {280} :[S @ 0x00000000fae01c20
 - _nonstatic_field_size:     {360} :1
 - _static_field_size:     {364} :1
 - _static_oop_field_count:     {368} :0
 - _nonstatic_oop_map_size:     {372} :0
 - _is_marked_dependent:     {376} :0
 - _init_state:     {498} :5
 - _vtable_len:     {392} :6
 - _itable_len:     {396} :2

////////////////////////////////////////
OOP.KLASS.MIRROR#sun.jvm.hotspot.oops.Instance@ef44eaa0
Oop for java/lang/Class @ 0x00000000ef44eaa0 (object size = 96)
 - _mark:     {0} :1
 - _metadata._compressed_klass:     {8} :InstanceKlass for java/lang/Class @ 0x00000000fae160c0
 - cachedConstructor:     {12} :null
 - newInstanceCallerCache:     {16} :null
 - name:     {20} :null
 - classLoader:     {24} :Oop for sun/misc/Launcher$AppClassLoader @ 0x00000000ef442c58
 - reflectionData:     {28} :null
 - classRedefinedCount:     {72} :0
 - genericInfo:     {32} :null
 - enumConstants:     {36} :null
 - enumConstantDirectory:     {40} :null
 - annotations:     {44} :null
 - declaredAnnotations:     {48} :null
 - lastAnnotationsRedefinedCount:     {76} :0
 - annotationType:     {52} :null
 - classValueMap:     {56} :null
Oop for java/lang/Class @ 0x00000000ef44eaa0 (object size = 96)
 - wk_static_i:     {88} :7777777


////////////////////////////////////////
OOP.KLASS.KLASS#sun.jvm.hotspot.oops.InstanceKlassKlass@fae00270
InstanceKlassKlass @ 0x00000000fae00270 (object size = 208)
 - _mark:     {0} :1
 - _metadata._compressed_klass:     {8} :KlassKlass @ 0x00000000fae00000
 - _java_mirror:     {120} :null
 - _super:     {128} :null
 - _layout_helper:     {24} :0
 - _access_flags:     {156} :0
 - _subklass:     {136} :null
 - _next_sibling:     {144} :null
 - _alloc_count:     {160} :0

////////////////////////////////////////
OOP.KLASS.KLASS.KLASS#sun.jvm.hotspot.oops.KlassKlass@fae00000
KlassKlass @ 0x00000000fae00000 (object size = 208)
 - _mark:     {0} :1
 - _metadata._compressed_klass:     {8} :KlassKlass @ 0x00000000fae00000
 - _java_mirror:     {120} :null
 - _super:     {128} :null
 - _layout_helper:     {24} :0
 - _access_flags:     {156} :0
 - _subklass:     {136} :null
 - _next_sibling:     {144} :null
 - _alloc_count:     {160} :0

////////////////////////////////////////
OOP.KLASS.KLASS.KLASS.KLASS#sun.jvm.hotspot.oops.KlassKlass@fae00000
KlassKlass @ 0x00000000fae00000 (object size = 208)
 - _mark:     {0} :1
 - _metadata._compressed_klass:     {8} :KlassKlass @ 0x00000000fae00000
 - _java_mirror:     {120} :null
 - _super:     {128} :null
 - _layout_helper:     {24} :0
 - _access_flags:     {156} :0
 - _subklass:     {136} :null
 - _next_sibling:     {144} :null
 - _alloc_count:     {160} :0