Android JNI本地引用表，转储当前状态

Question

Any Android JNI developer should be familiar with this wonderful message in logcat. My question is: how can I tell the VM to dump current table state? I need it for debugging purposes to make sure that native threads at exit have no outstanding local references.

Answer 1

Full credit to Pavel, but I thought others might like the example code:

jclass vm_class = env->FindClass("dalvik/system/VMDebug");
jmethodID dump_mid = env->GetStaticMethodID( vm_class, "dumpReferenceTables", "()V" );
env->CallStaticVoidMethod( vm_class, dump_mid );

Answer 2

如果有人需要做类似的事情，你可以使用dalvik.system.VMDebug中的dumpReferenceTables

Answer 3

I try code below.it works well.

try {
    Class cls = Class.forName("android.os.Debug");
    Method method = cls.getDeclaredMethod("dumpReferenceTables");
    Constructor con= cls.getDeclaredConstructor();
    con.setAccessible(true);
    method.invoke(con.newInstance());
    //call method dumpReferenceTables of dalvik.system.VMDebug
    //to dump reference table at last.
}
catch(Exception e){
    Log.i(TAG,"exception="+e.getMessage());
}

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I/art (28913): global reference table dump:

I/art (28913): Last 10 entries (of 267):

I/art (28913): 266: 0x12e340c0 java.lang.ref.WeakReference

I/art (28913): 265: 0x12e34060 java.lang.ref.WeakReference

I/art (28913): 264: 0x12e24220 java.lang.ref.WeakReference

I/art (28913): 263: 0xa1ba5000 byte[] (2710656 elements)

I/art (28913): 262: 0xa284d000 byte[] (30276 elements)

I/art (28913): 261: 0xa2855000 byte[] (19312 elements)

I/art (28913): 260: 0xa1e3b000 byte[] (6529728 elements)

I/art (28913): 259: 0x12e1ca60 android.view.accessibility.AccessibilityManager$1

I/art (28913): 258: 0x12df2c70 android.content.ContentProvider$Transport

I/art (28913): 257: 0x12ed4040 java.lang.ref.WeakReference

I/art (28913): Summary:

I/art (28913): 2 of android.opengl.EGLContext (2 unique instances)

I/art (28913): 1 of android.hardware.display.DisplayManagerGlobal$DisplayManagerCallback

I/art (28913): 223 of java.lang.Class (172 unique instances)

I/art (28913): 2 of android.opengl.EGLDisplay (2 unique instances)

I/art (28913): 2 of java.lang.ThreadGroup (2 unique instances)

I/art (28913): 2 of android.opengl.EGLSurface (2 unique instances)

I/art (28913): 1 of dalvik.system.VMRuntime

I/art (28913): 1 of android.content.ContentProvider$Transport

I/art (28913): 1 of dalvik.system.PathClassLoader

I/art (28913): 1 of android.view.accessibility.AccessibilityManager$1

I/art (28913): 1 of android.app.ActivityThread$ApplicationThread

I/art (28913): 2 of byte[] (100 elements) (2 unique instances)

I/art (28913): 7 of byte[] (8192 elements) (7 unique instances)

I/art (28913): 1 of byte[] (19312 elements)

I/art (28913): 1 of byte[] (30276 elements)

I/art (28913): 1 of byte[] (2710656 elements)

I/art (28913): 1 of byte[] (6529728 elements)

I/art (28913): 2 of java.lang.String (2 unique instances)

I/art (28913): 15 of java.lang.ref.WeakReference (15 unique instances)