1、什麼是 ANR?
ANR:Application Not Responding，即應用無響應
ANR一般有三種類型：
1. KeyDispatchTimeout(5 seconds) --主要類型按鍵或觸摸事件在特定時間內無響應
2. BroadcastTimeout(10 seconds) --BroadcastReceiver在特定時間內無法處理完成
3. ServiceTimeout(20 seconds) --小概率類型 Service在特定的時間內無法處理完成
3、KeyDispatchTimeout：
Akey or touch event was not dispatched within the specified time（按鍵或觸摸事件在特定時間內無響應）
具體的超時時間的定義在framework下的ActivityManagerService.java
//How long we wait until we timeout on key dispatching.
staticfinal int KEY_DISPATCHING_TIMEOUT = 5*1000
超時原因分析：
超時時間的計數一般是從按鍵分發給app開始。超時的原因一般有兩種：
(1)當前的事件沒有機會得到處理（即UI線程正在處理前一個事件，沒有及時的完成或者looper被某種原因阻塞住了）
(2)當前的事件正在處理，但沒有及時完成
4、BroadcastTimeout及ServiceTimeout：
BroadcastReceive 及Service實際上都是在UI線程中執行，如果在規定的時間內無法完成，就會阻塞主線程。
5、解決方法：
1. UI線程儘量只做跟UI相關的工作
2. 耗時的工作（比如數據庫操作，I/O，連接網絡或者別的有可能阻礙UI線程的操作）把它放入單獨的線程處理
3. 儘量用Handler來處理UIthread和別的thread之間的交互
4.在BroadcastReceive和Service中執行耗時操作時，使用IntentService執行耗時操作
UI線程主要包括如下：
1. Activity:onCreate(), onResume(), onDestroy(), onKeyDown(), onClick(),etc
2. AsyncTask: onPreExecute(), onProgressUpdate(), onPostExecute(), onCancel,etc
3. Mainthread handler: handleMessage(), post*(runnable r), etc
4. other
7、如何去分析ANR?
先看個LOG:
04-01 13:12:11.572 I/InputDispatcher( 220): Application is not responding:Window{2b263310com.android.email/com.android.email.activity.SplitScreenActivitypaused=false}. 5009.8ms since event, 5009.5ms since waitstarted 04-0113:12:11.572 I/WindowManager( 220): Input event dispatching timedout sending tocom.android.email/com.android.email.activity.SplitScreenActivity 04-01 13:12:14.123 I/Process( 220): Sending signal. PID: 21404 SIG: 3---發生ANR的時間和生成trace.txt的時間 04-01 13:12:14.123 I/dalvikvm(21404):threadid=4: reacting to signal 3 …… 04-0113:12:15.872 E/ActivityManager( 220): ANR in com.android.email(com.android.email/.activity.SplitScreenActivity) 04-0113:12:15.872 E/ActivityManager( 220): Reason:keyDispatchingTimedOut 04-0113:12:15.872 E/ActivityManager( 220): Load: 8.68 / 8.37 / 8.53 04-0113:12:15.872 E/ActivityManager( 220): CPUusage from 4361ms to 699ms ago ----CPU在ANR發生前的使用情況 04-0113:12:15.872 E/ActivityManager( 220): 5.5%21404/com.android.email: 1.3% user + 4.1% kernel / faults: 10 minor 04-0113:12:15.872 E/ActivityManager( 220): 4.3%220/system_server: 2.7% user + 1.5% kernel / faults: 11 minor 2 major 04-0113:12:15.872 E/ActivityManager( 220): 0.9%52/spi_qsd.0: 0% user + 0.9% kernel 04-0113:12:15.872 E/ActivityManager( 220): 0.5%65/irq/170-cyttsp-: 0% user + 0.5% kernel 04-0113:12:15.872 E/ActivityManager( 220): 0.5%296/com.android.systemui: 0.5% user + 0% kernel 04-0113:12:15.872 E/ActivityManager( 220): 100%TOTAL: 4.8% user + 7.6% kernel + 87% iowait 04-0113:12:15.872 E/ActivityManager( 220): CPUusage from 3697ms to 4223ms later:-- ANR後CPU的使用量 04-0113:12:15.872 E/ActivityManager( 220): 25%21404/com.android.email: 25% user + 0% kernel / faults: 191 minor 04-0113:12:15.872 E/ActivityManager( 220): 16% 21603/__eas(par.hakan: 16% user + 0% kernel 04-0113:12:15.872 E/ActivityManager( 220): 7.2% 21406/GC: 7.2% user + 0% kernel 04-0113:12:15.872 E/ActivityManager( 220): 1.8% 21409/Compiler: 1.8% user + 0% kernel 04-0113:12:15.872 E/ActivityManager( 220): 5.5%220/system_server: 0% user + 5.5% kernel / faults: 1 minor 04-0113:12:15.872 E/ActivityManager( 220): 5.5% 263/InputDispatcher: 0% user + 5.5% kernel 04-0113:12:15.872 E/ActivityManager( 220): 32%TOTAL: 28% user + 3.7% kernel從LOG可以看出ANR的類型，CPU的使用情況，如果CPU使用量接近100%，說明當前設備很忙，有可能是CPU飢餓導致了ANR
如果CPU使用量很少，說明主線程被BLOCK了
如果IOwait很高，說明ANR有可能是主線程在進行I/O操作造成的
除了看LOG，解決ANR還得需要trace.txt文件，
如何獲取呢？可以用如下命令獲取
$chmod 777 /data/anr
$rm /data/anr/traces.txt
$ps
$kill -3 PID
adbpull data/anr/traces.txt ./mytraces.txt
從trace.txt文件，看到最多的是如下的信息：
-----pid 21404 at 2011-04-01 13:12:14 ----- Cmdline: com.android.email DALVIK THREADS: (mutexes: tll=0tsl=0 tscl=0 ghl=0 hwl=0 hwll=0) "main" prio=5 tid=1NATIVE | group="main" sCount=1 dsCount=0obj=0x2aad2248 self=0xcf70 | sysTid=21404 nice=0 sched=0/0cgrp=[fopen-error:2] handle=1876218976 atandroid.os.MessageQueue.nativePollOnce(Native Method) atandroid.os.MessageQueue.next(MessageQueue.java:119) atandroid.os.Looper.loop(Looper.java:110) at android.app.ActivityThread.main(ActivityThread.java:3688) at java.lang.reflect.Method.invokeNative(Native Method) atjava.lang.reflect.Method.invoke(Method.java:507) atcom.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:624) at dalvik.system.NativeStart.main(Native Method) 8、Thread狀態
ThreadState (defined at “dalvik/vm/thread.h “)
THREAD_UNDEFINED = -1, /* makes enum compatible with int32_t */
THREAD_ZOMBIE = 0, /* TERMINATED */
THREAD_RUNNING = 1, /* RUNNABLE or running now */
THREAD_TIMED_WAIT = 2, /* TIMED_WAITING in Object.wait() */
THREAD_MONITOR = 3, /* BLOCKED on a monitor */
THREAD_WAIT = 4, /* WAITING in Object.wait() */
THREAD_INITIALIZING= 5, /* allocated, not yet running */
THREAD_STARTING = 6, /* started, not yet on thread list */
THREAD_NATIVE = 7, /* off in a JNI native method */
THREAD_VMWAIT = 8, /* waiting on a VM resource */
THREAD_SUSPENDED = 9, /* suspended, usually by GC or debugger */
9、如何調查並解決ANR
1. 首先分析log
2. 從trace.txt文件查看調用stack.
3. 看代碼
4. 仔細查看ANR的成因（iowait?block?memoryleak?）
10、案例：
案例1：關鍵詞:ContentResolver in AsyncTask onPostExecute, high iowait
原因：IOWait很高，說明當前系統在忙於I/O，因此數據庫操作被阻塞
final Message message=Message.restoreMessageWithId(mProviderContext,messageId); if(message==null){ return;}Account account=Account.restoreAccountWithId(mProviderContext,message.mAccountKey);if(account==null){ return;//isMessagingController returns false for null, but let's make itclear.}if(isMessagingController(account)){ new Thread(){ @Override public void run(){ mLegacyController.processPendingActions(message.mAccountKey); }}.start();}解決後：
newThread() { finalMessagemessage=Message.restoreMessageWithId(mProviderContext,messageId); if(message==null){ return; } Accountaccount=Account.restoreAccountWithId(mProviderContext,message.mAccountKey); if(account==null){ return;//isMessagingController returns false for null, but let's make itclear. } if(isMessagingController(account)) { mLegacyController.processPendingActions(message.mAccountKey); }}.start();關於AsyncTask:http://developer.android.com/reference/android/os/AsyncTask.html
案例2：關鍵詞:在UI線程進行網絡數據的讀寫
ANRin process: com.android.mediascape:PhotoViewer (last incom.android.mediascape:PhotoViewer) Annotation:keyDispatchingTimedOut CPU usage: Load: 6.74 / 6.89 / 6.12 CPUusage from 8254ms to 3224ms ago: ovider.webmedia: 4% = 4% user +0% kernel / faults: 68 minor system_server: 2% = 1% user + 0%kernel / faults: 18 minor re-initialized>: 0% = 0% user + 0%kernel / faults: 50 minor events/0: 0% = 0% user + 0%kernel TOTAL:7% = 6% user + 1% kernel DALVIKTHREADS: ""main"" prio=5 tid=3 NATIVE |group=""main"" sCount=1 dsCount=0 s=Yobj=0x4001b240 self=0xbda8 | sysTid=2579 nice=0 sched=0/0cgrp=unknown handle=-1343993184 atorg.apache.harmony.luni.platform.OSNetworkSystem.receiveStreamImpl(NativeMethod) atorg.apache.harmony.luni.platform.OSNetworkSystem.receiveStream(OSNetworkSystem.java:478) atorg.apache.harmony.luni.net.PlainSocketImpl.read(PlainSocketImpl.java:565) atorg.apache.harmony.luni.net.SocketInputStream.read(SocketInputStream.java:87) atorg.apache.harmony.luni.internal.net.www.protocol.http.HttpURLConnection$LimitedInputStream.read(HttpURLConnection.java:303) atjava.io.InputStream.read(InputStream.java:133) atjava.io.BufferedInputStream.fillbuf(BufferedInputStream.java:157) atjava.io.BufferedInputStream.read(BufferedInputStream.java:346) atandroid.graphics.BitmapFactory.nativeDecodeStream(Native Method) atandroid.graphics.BitmapFactory.decodeStream(BitmapFactory.java:459) atcom.android.mediascape.activity.PhotoViewerActivity.getPreviewImage(PhotoViewerActivity.java:4465) atcom.android.mediascape.activity.PhotoViewerActivity.dispPreview(PhotoViewerActivity.java:4406) atcom.android.mediascape.activity.PhotoViewerActivity.access$6500(PhotoViewerActivity.java:125) atcom.android.mediascape.activity.PhotoViewerActivity$33$1.run(PhotoViewerActivity.java:4558) atandroid.os.Handler.handleCallback(Handler.java:587) atandroid.os.Handler.dispatchMessage(Handler.java:92) atandroid.os.Looper.loop(Looper.java:123) atandroid.app.ActivityThread.main(ActivityThread.java:4370) atjava.lang.reflect.Method.invokeNative(Native Method) atjava.lang.reflect.Method.invoke(Method.java:521) atcom.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) atcom.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) atdalvik.system.NativeStart.main(Native Method)關於網絡連接，在設計的時候可以設置個timeout的時間或者放入獨立的線程來處理。
關於Handler的問題，可以參考：http://developer.android.com/reference/android/os/Handler.html
案例3：關鍵詞：Memoryleak/Thread leak
11-1621:41:42.560 I/ActivityManager( 1190): ANR in process:android.process.acore (last in android.process.acore) 11-1621:41:42.560 I/ActivityManager( 1190): Annotation:keyDispatchingTimedOut 11-16 21:41:42.560 I/ActivityManager(1190): CPU usage: 11-16 21:41:42.560 I/ActivityManager( 1190):Load: 11.5 / 11.1 / 11.09 11-16 21:41:42.560 I/ActivityManager(1190): CPU usage from 9046ms to 4018ms ago: 11-16 21:41:42.560I/ActivityManager( 1190): d.process.acore:98%= 97% user + 0% kernel / faults: 1134 minor 11-16 21:41:42.560I/ActivityManager( 1190): system_server: 0% = 0% user + 0% kernel /faults: 1 minor 11-16 21:41:42.560 I/ActivityManager( 1190): adbd:0% = 0% user + 0% kernel 11-16 21:41:42.560 I/ActivityManager(1190): logcat: 0% = 0% user + 0% kernel 11-16 21:41:42.560I/ActivityManager( 1190): TOTAL:100% = 98% user + 1% kernel Cmdline: android.process.acore DALVIK THREADS: "main"prio=5 tid=3 VMWAIT |group="main" sCount=1 dsCount=0 s=N obj=0x40026240self=0xbda8 | sysTid=1815 nice=0 sched=0/0 cgrp=unknownhandle=-1344001376 atdalvik.system.VMRuntime.trackExternalAllocation(NativeMethod) atandroid.graphics.Bitmap.nativeCreate(Native Method) atandroid.graphics.Bitmap.createBitmap(Bitmap.java:468) atandroid.view.View.buildDrawingCache(View.java:6324) atandroid.view.View.getDrawingCache(View.java:6178) atandroid.view.ViewGroup.drawChild(ViewGroup.java:1541) …… atcom.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1830) atandroid.view.ViewRoot.draw(ViewRoot.java:1349) atandroid.view.ViewRoot.performTraversals(ViewRoot.java:1114) atandroid.view.ViewRoot.handleMessage(ViewRoot.java:1633) atandroid.os.Handler.dispatchMessage(Handler.java:99) atandroid.os.Looper.loop(Looper.java:123) atandroid.app.ActivityThread.main(ActivityThread.java:4370) atjava.lang.reflect.Method.invokeNative(Native Method) atjava.lang.reflect.Method.invoke(Method.java:521) atcom.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) atcom.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) atdalvik.system.NativeStart.main(Native Method) "Thread-408"prio=5 tid=329 WAIT |group="main" sCount=1 dsCount=0 s=N obj=0x46910d40self=0xcd0548 | sysTid=10602 nice=0 sched=0/0 cgrp=unknownhandle=15470792 at java.lang.Object.wait(Native Method) -waiting on <0x468cd420> (a java.lang.Object) atjava.lang.Object.wait(Object.java:288) atcom.android.dialer.CallLogContentHelper$UiUpdaterExecutor$1.run(CallLogContentHelper.java:289) atjava.lang.Thread.run(Thread.java:1096)分析：
atdalvik.system.VMRuntime.trackExternalAllocation(NativeMethod)內存不足導致block在創建bitmap上
**MEMINFO in pid 1360 [android.process.acore] **
native dalvik other total
size: 17036 23111 N/A 40147
allocated: 16484 20675 N/A 37159
free: 296 2436 N/A 2732
解決：如果機器的內存族，可以修改虛擬機的內存爲36M或更大，不過最好是複查代碼，查看哪些內存沒有釋放