用 jdb 追踪 Android

You may have debug Android in eclipse, Have you ever used jdb tracing Android. Since Dalvikvm support jdwp, we can use jdb to debug the program. there are 2 ways

Android as debug host

Steps

1) update libandroid_runtime

change below

frameworks/base/core/jni/AndroidRuntime.cpp    620     opt.optionString =    621         "-agentlib:jdwp=transport=dt_android_adb,suspend=n,server=y";asopt.optionString = "-agentlib:jdwp=transport=dt_socket,address=8011,server=y,suspend=y";

use "mmm frameworks/base/core/jni" to re-generate system/lib/libandroid_runtime.so, then copy to your runing env (system/lib)

2) change system/root/default.prop on your running env

change "ro.debuggable=0" to "ro.debuggable=1"

if you won not do it, you can specify AndroidManifest.xml

Or the App can not be debugged

3) start the app

check stop you will see below

I/Zygote  ( 6843/6843): Accepting command socket connectionsI/jdwp    ( 7385/7385): JDWP will wait for debugger on port 8011

4) use jdb to attach the port

jdb -attach localhost:8011

--- you will see ---

Initializing jdb ...>VM Started: "thread=<1> main", dalvik.system.Zygote.nativeForkSystemServer(), line=-1 bci=-1<1> main[1]

5) include source dirs by "use" command, you will see source code

<1> main[1] use /home/user/jb/frameworks/base/core/java:/home/user/jb/frameworks/base/packages/SettingsProvider/src/:/home/user/jb/frameworks/base/services/java

6) set break and trace

Use commands: stop in, cont, list, next, you will able to trace your code<1> main[1] stop in com.android.server.InputMethodManagerService.getEnabledInputMethodSubtypeListDeferring breakpoint com.android.server.InputMethodManagerService.getEnabledInputMethodSubtypeList.<1> main[1] cont> Ignoring cmd 268435570/199/1 from the VMSet deferred breakpoint com.android.server.InputMethodManagerService.getEnabledInputMethodSubtypeListBreakpoint hit: "thread=<12> android.server.ServerThread", com.android.server.InputMethodManagerService.getEnabledInputMethodSubtypeList(), line=845 bci=0845            synchronized (mMethodMap) { <12> android.server.ServerThread[1] list841    842        @Override843        public List<InputMethodSubtype> getEnabledInputMethodSubtypeList(InputMethodInfo imi,844                boolean allowsImplicitlySelectedSubtypes) {845 =>         synchronized (mMethodMap) {846                return getEnabledInputMethodSubtypeListLocked(imi, allowsImplicitlySelectedSubtypes);847            }848        }849    850        @Override<12> android.server.ServerThread[1] nextStep completed: "thread=<12> android.server.ServerThread", com.android.server.InputMethodManagerService.getEnabledInputMethodSubtypeList(), line=846 bci=3846                return getEnabledInputMethodSubtypeListLocked(imi, allowsImplicitlySelectedSubtypes);<12> android.server.ServerThread[1]

Jdb as debug host

There are shortcomings in "Android as host", because every time the JavaVM starts up, it will move to listen status, So the SystemServer will listen, even we don't want to. so "Jdb as debug host" is a better idea.

1) update libandroid_runtime

change below

frameworks/base/core/jni/AndroidRuntime.cpp    620     opt.optionString =    621         "-agentlib:jdwp=transport=dt_android_adb,suspend=n,server=y";asopt.optionString = "-agentlib:jdwp=transport=dt_socket,address=localhost:8011,server=n,suspend=y";

if you won't run jdb on the same host, change "localhost" to other host/ip

2) change system/root/default.prop on your running env

change "ro.debuggable=0" to "ro.debuggable=1"

3) use jdb to listen the port

jdb -listen 8011

4) Start Android or APPs

when your Dalvik VM start, it will connect 8011

The good advantages of "Jdb as Host" is that when you need to debug, you let jdb listen; if you won't listen, Android will run as normal.

For example, when I want to debug the App, I run "jdb -listen 8011", then I click the App icon on the Launcher and start to debug.

Attention:

The Apps have launch timeout limits or It will be terminated by AM, when you enter jdb console, you need to quickly set breakpoint, and enter "cont" to run

Android as debug host

1) update libandroid_runtime

2) change system/root/default.prop on your running env

3) start the app

4) use jdb to attach the port

5) include source dirs by "use" command, you will see source code

Jdb as debug host

1) update libandroid_runtime

2) change system/root/default.prop on your running env

3) use jdb to listen the port

4) Start Android or APPs

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