如何避免KeyDispatchTimeout
1：UI线程尽量只做跟UI相关的工作
2：耗时的工作（比如数据库操作，I/O，连接网络或者别的有可能阻碍UI线程的操作）把它放入单独的线程处理
3：尽量用Handler来处理UIthread和别的thread之间的交互
如何去分析ANR
DALVIK THREADS (22):
"main" prio=5 tid=1 Native
| group="main" sCount=1 dsCount=0 obj=0x74729000 self=0xf4827800
| sysTid=29242 nice=0 cgrp=default sched=0/0 handle=0xf7779bec
| state=D schedstat=( 1168866313 28837852 971 ) utm=90 stm=26 core=5 HZ=100
| stack=0xff5f3000-0xff5f5000 stackSize=8MB
| held mutexes=
kernel: (couldn't read /proc/self/task/29242/stack)
native: (backtrace::Unwind failed for thread 29242)
at libcore.io.Posix.fsync(Native method)
at libcore.io.BlockGuardOs.fsync(BlockGuardOs.java:143)
at java.io.FileDescriptor.sync(FileDescriptor.java:74)
at android.os.FileUtils.sync(FileUtils.java:152)
at android.app.SharedPreferencesImpl.writeToFile(SharedPreferencesImpl.java:598)
at android.app.SharedPreferencesImpl.access$800(SharedPreferencesImpl.java:51)
at android.app.SharedPreferencesImpl$2.run(SharedPreferencesImpl.java:512)
- locked <@addr=0x32c014d0> (a java.lang.Object)
at android.app.SharedPreferencesImpl.enqueueDiskWrite(SharedPreferencesImpl.java:533)
at android.app.SharedPreferencesImpl.access$100(SharedPreferencesImpl.java:51)
at android.app.SharedPreferencesImpl$EditorImpl.commit(SharedPreferencesImpl.java:455)
at com.zhangyue.iReader.DB.SPHelper.setString(SourceFile:56)
- locked <@addr=0x32c01810> (a com.zhangyue.iReader.DB.SPHelper)
at com.zhangyue.iReader.account.a.a(SourceFile:533)
at com.zhangyue.iReader.account.a.b(SourceFile:526)
at com.zhangyue.iReader.account.a.a(SourceFile:215)
at com.zhangyue.iReader.app.APP.initAPP(SourceFile:681)
at com.zhangyue.iReader.app.APP.initAPPData(SourceFile:731)
at com.zhangyue.iReader.app.IreaderApplication.onCreate(SourceFile:53)
at com.ireader.plug.utils.a.a(unavailable:-1)
at com.ireader.plug.api.IreaderPlugApi.initPlugin(unavailable:-1)
at com.android.browser.Browser.onCreate(SourceFile:77)
at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1024)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:5084)
at android.app.ActivityThread.access$1600(ActivityThread.java:187)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1646)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5871)
at java.lang.reflect.Method.invoke!(Native method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1119)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:885)
"Heap thread pool worker thread 0" prio=5 tid=2 Native (still starting up)
| group="" sCount=1 dsCount=0 obj=0x0 self=0xeec4d400
| sysTid=29250 nice=0 cgrp=default sched=0/0 handle=0xf5078000
| state=S schedstat=( 616307 0 18 ) utm=0 stm=0 core=7 HZ=100
| stack=0xf4390000-0xf4392000 stackSize=1020KB
| held mutexes=
kernel: (couldn't read /proc/self/task/29250/stack)
native: #00 pc 000134a4 /system/lib/libc.so (syscall+28)
native: #01 pc 000a9b27 /system/lib/libart.so (art::ConditionVariable::Wait(art::Thread*)+74)
native: #02 pc 00237b0f /system/lib/libart.so (art::ThreadPool::GetTask(art::Thread*)+50)
native: #03 pc 00237ab9 /system/lib/libart.so (art::ThreadPoolWorker::Run()+52)
native: #04 pc 002382e1 /system/lib/libart.so (art::ThreadPoolWorker::Callback(void*)+52)
native: #05 pc 00016f97 /system/lib/libc.so (__pthread_start(void*)+30)
native: #06 pc 00014f9f /system/lib/libc.so (__start_thread+6)
(no managed stack frames)
拿到一个日志文件，要分成多段来看 。 log文件很长，其中包含十几个小单元信息，但不要被吓到 ，事实上他主要由三大块儿组成 。
1，系统基本信息 ，包括 内存，CPU ，进程队列 ，虚拟内存 ， 垃圾回收等信息 。------ MEMORY INFO (/proc/meminfo) ------
------ CPU INFO (top -n 1 -d 1 -m 30 -t) ------
------ PROCRANK (procrank) ------
------ VIRTUAL MEMORY STATS (/proc/vmstat) ------
------ VMALLOC INFO (/proc/vmallocinfo) ------
格式如下：
------ MEMORY INFO (/proc/meminfo) ------
MemTotal: 347076 kB
MemFree: 56408 kB
Buffers: 7192 kB
Cached: 104064 kB
SwapCached: 0 kB
Active: 192592 kB
Inactive: 40548 kB
Active(anon): 129040 kB
Inactive(anon): 1104 kB
Active(file): 63552 kB
Inactive(file): 39444 kB
Unevictable: 7112 kB
Mlocked: 0 kB
SwapTotal: 0 kB
SwapFree: 0 kB
Dirty: 44 kB
Writeback: 0 kB
AnonPages: 129028 kB
Mapped: 73728 kB
Shmem: 1148 kB
Slab: 13072 kB
SReclaimable: 4564 kB
SUnreclaim: 8508 kB
KernelStack: 3472 kB
PageTables: 12172 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 173536 kB
Committed_AS: 7394524 kB
VmallocTotal: 319488 kB
VmallocUsed: 90752 kB
VmallocChunk: 181252 kB
2，时间信息 ， 也是我们主要分析的信息 。
------ VMALLOC INFO (/proc/vmallocinfo) ------
------ EVENT INFO (/proc/vmallocinfo) ------
格式如下：
------ SYSTEM LOG (logcat -b system -v time -d *:v) ------
01-15 16:41:43.671 W/PackageManager( 2466): Unknown permission com.wsomacp.permission.PROVIDER in package com.android.mms
01-15 16:41:43.671 I/ActivityManager( 2466): Force stopping package com.android.mms uid=10092
01-15 16:41:43.675 I/UsageStats( 2466): Something wrong here, didn’t expect com.sec.android.app.twlauncher to be paused
01-15 16:41:44.108 I/ActivityManager( 2466): Start proc com.sec.android.widgetapp.infoalarm for service com.sec.android.widgetapp.infoalarm/.engine.DataService: pid=20634 uid=10005 gids={3003, 1015, 3002}
01-15 16:41:44.175 W/ActivityManager( 2466): Activity pause timeout for HistoryRecord{48589868 com.sec.android.app.twlauncher/.Launcher}
01-15 16:41:50.864 I/KeyInputQueue( 2466): Input event
01-15 16:41:50.866 D/KeyInputQueue( 2466): screenCaptureKeyFlag setting 0
01-15 16:41:50.882 I/PowerManagerService( 2466): Ulight 0->7|0
01-15 16:41:50.882 I/PowerManagerService( 2466): Setting target 2: cur=0.0 target=70 delta=4.6666665 nominalCurrentValue=0
01-15 16:41:50.882 I/PowerManagerService( 2466): Scheduling light animator!
01-15 16:41:51.706 D/PowerManagerService( 2466): enableLightSensor true
01-15 16:41:51.929 I/KeyInputQueue( 2466): Input event
01-15 16:41:51.933 W/WindowManager( 2466): No focus window, dropping: KeyEvent{action=0 code=26 repeat=0 meta=0 scancode=26 mFlags=9}
3，虚拟机信息 ， 包括进程的，线程的跟踪信息，这是用来跟踪进程和线程具体点的好地方 。
------ VM TRACES JUST NOW (/data/anr/traces.txt.bugreport: 2011-01-15 16:49:02) ------
------ VM TRACES AT LAST ANR (/data/anr/traces.txt: 2011-01-15 16:49:02) ------
格式如下 ：
----- pid 21161 at 2011-01-15 16:49:01 -----
Cmd line: com.android.mms
DALVIK THREADS:
"main" prio=5 tid=1 NATIVE
| group="main" sCount=1 dsCount=0 s=N obj=0x4001d8d0 self=0xccc8
| sysTid=21161 nice=0 sched=0/0 cgrp=default handle=-1345017808
| schedstat=( 4151552996 5342265329 10995 )
at android.media.MediaPlayer._reset(Native Method)
at android.media.MediaPlayer.reset(MediaPlayer.java:1218)
at android.widget.VideoView.release(VideoView.java:499)
at android.widget.VideoView.access$2100(VideoView.java:50)
at android.widget.VideoView$6.surfaceDestroyed(VideoView.java:489)
at android.view.SurfaceView.reportSurfaceDestroyed(SurfaceView.java:572)
at android.view.SurfaceView.updateWindow(SurfaceView.java:476)
at android.view.SurfaceView.onWindowVisibilityChanged(SurfaceView.java:206)
at android.view.View.dispatchDetachedFromWindow(View.java:6082)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1156)
at android.view.ViewGroup.removeAllViewsInLayout(ViewGroup.java:2296)
at android.view.ViewGroup.removeAllViews(ViewGroup.java:2254)
at com.android.mms.ui.SlideView.reset(SlideView.java:687)
at com.android.mms.ui.SlideshowPresenter.presentSlide(SlideshowPresenter.java:189)
at com.android.mms.ui.SlideshowPresenter$3.run(SlideshowPresenter.java:531)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4627)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
at dalvik.system.NativeStart.main(Native Method)
我总结了观察log文件的基本步骤 。
1，如果是ANR问题 ， 则搜索“ANR ”关键词 。 快速定位到关键事件信息 。
2，如果是ForceClosed 和其它异常退出信息，则搜索"Fatal" 关键词， 快速定位到关键事件信息 。如果是crash,则搜索CRASH.
3，定位到关键事件信息后 ， 如果信息不够明确的，再去搜索应用程序包的虚拟机信息 ，查看具体的进程和线程跟踪的日志，来定位到代码 。 搜索 DALVIK THREADS ，查看tid=1的进程的情况
4, 搜索你的包名，进程名等。
用这种方法，出现问题，根本不需要断点调试 ， 直接定位到问题，屡试不爽 。
下面，我们就开始来分析这个例子的log 。
打开log文件 ， 由于是ANR错误，因此搜索"ANR " ， 为何要加空格呢，你加上和去掉比较一下就知道了 。 可以屏蔽掉不少保存到anr.log文件的无效信息 。