Android ANR初探

前言

記得之前換工作面試的時(shí)候，面試官問(wèn)我知道ANR嗎？我說(shuō)知道，然后讓我講了一下ANR出現(xiàn)的原因，我就把ANR出現(xiàn)的原因一通說(shuō)。然后，面試官又問(wèn)我那么怎么分析和解決ANR問(wèn)題呢？這時(shí)候我就傻眼了，只能說(shuō)分析代碼了。然后面試官笑了一下，又問(wèn)我：那么你知道ANR會(huì)生成一個(gè)ANR文件嗎？當(dāng)時(shí)的我該怎么形容呢？硬著頭皮說(shuō)不知道。當(dāng)然，那次也就GG了。

首先

那么什么是ANR呢？

  • 1、解釋

    Application Not Responding即應(yīng)用無(wú)響應(yīng)。

當(dāng)操作在一段時(shí)間內(nèi)，系統(tǒng)無(wú)法處理是，就會(huì)發(fā)生ANR。彈出對(duì)應(yīng)的無(wú)響應(yīng)的對(duì)話框。

  • 2、ANR的類型

1）KeyDispatchTimeout
這個(gè)Key事件分發(fā)超時(shí)的時(shí)間，Android默認(rèn)是5秒，主要是定義在ActivityManagerService.java

// How long we wait until we timeout on key dispatching.
static final int KEY_DISPATCHING_TIMEOUT = 5*1000;

2）BroadcastTimeOut
廣播的超時(shí)時(shí)間，分為FG和BG，分別是10秒和60秒。同樣是定義在ActivitManagerService.java

// How long we allow a receiver to run before giving up on it.
static final int BROADCAST_FG_TIMEOUT = 10*1000;
static final int BROADCAST_BG_TIMEOUT = 60*1000;

3）ServiceTimeOut
Service的超時(shí)時(shí)間為20秒，定義在ActiveServices.java

// How long we wait for a service to finish executing.
static final int SERVICE_TIMEOUT = 20*1000;

// How long we wait for a service to finish executing.
static final int SERVICE_BACKGROUND_TIMEOUT = SERVICE_TIMEOUT * 10;

其次

上面說(shuō)了那么多，那么我們來(lái)模擬一下ANR并且分析一下
1、首先創(chuàng)建一個(gè)activity，里面放兩個(gè)按鈕，當(dāng)我們點(diǎn)擊選擇相冊(cè)的按鈕的時(shí)候先讓主線程休眠50s，然后看看

class MainActivity : AppCompatActivity() {


override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    btn_album.setOnClickListener {
        Thread.sleep(50*1000)
        CameraUtil.openAlbum(this, REQUEST_CODE_OPEN_PHOTO_ALBUM)
    }
    btn_take_photo.setOnClickListener {
        CameraUtil.takePhoto(this, REQUEST_CODE_TAKE_PHOTO)
    }
  }





override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    CameraUtil.onActivityResult(
        this,
        requestCode,
        resultCode,
        data,
        object : CameraUtil.OnCameraResultListener {
            override fun onAlbumResult(path: String) {
                Log.e("TAG", path)
            }

            override fun onCameraResult(uri: Uri) {
                Log.e("TAG", uri.toString())
            }
        })
}


}

ANR.png

分析:可以看到上面我們?cè)谥骶€程中讓主線程休眠50s，那么界面長(zhǎng)時(shí)間無(wú)響應(yīng)就會(huì)出現(xiàn)ANR了，如上圖所示。那么當(dāng)我們不知道為什么會(huì)出現(xiàn)ANR的時(shí)候該怎么處理呢？其實(shí)，當(dāng)出現(xiàn)ANR的時(shí)候會(huì)在data/anr/目錄下生成anr日志文件，這里以as為例。
ANR文件.png

1、如上圖所示，我們先點(diǎn)擊DeviceFile Explorer選項(xiàng)，然后打開(kāi)data/anr文件，里面的anr_2020-08-10-18-17-42就是我們所需要的anr文件。然后，右擊保存到電腦上，找到我們保存的地方打開(kāi)ANR文件看看里面的具體內(nèi)容。

2、ANR文件具體內(nèi)容

suspend all histogram:  Sum: 1.413ms 99% C.I. 2us-243.199us Avg: 13.586us Max: 352us
DALVIK THREADS (16):
"Signal Catcher" daemon prio=5 tid=3 Runnable
  | group="system" sCount=0 dsCount=0 flags=0 obj=0x15700020 self=0x7b7b016400
  | sysTid=13715 nice=0 cgrp=default sched=0/0 handle=0x7b5c6054f0
  | state=R schedstat=( 30247917 1431772 18 ) utm=1 stm=1 core=0 HZ=100
  | stack=0x7b5c50a000-0x7b5c50c000 stackSize=1009KB
  | held mutexes= "mutator lock"(shared held)
  native: #00 pc 00000000003c7d4c  /system/lib64/libart.so     (art::DumpNativeStack(std::__1::basic_ostream<char, std::__1::char_traits<char>>&, int,         BacktraceMap*, char const*, art::ArtMethod*, void*, bool)+220)
  native: #01 pc 00000000004a5b64  /system/lib64/libart.so     (art::Thread::DumpStack(std::__1::basic_ostream<char, std::__1::char_traits<char>>&, bool,     BacktraceMap*, bool) const+352)
  native: #02 pc 00000000004bf780  /system/lib64/libart.so (art::DumpCheckpoint::Run(art::Thread*)+844)
  native: #03 pc 00000000004b84fc  /system/lib64/libart.so (art::ThreadList::RunCheckpoint(art::Closure*, art::Closure*)+484)
  native: #04 pc 00000000004b798c  /system/lib64/libart.so (art::ThreadList::Dump(std::__1::basic_ostream<char, std::__1::char_traits<char>>&, bool)+1036)
  native: #05 pc 00000000004b74ac  /system/lib64/libart.so (art::ThreadList::DumpForSigQuit(std::__1::basic_ostream<char, std::__1::char_traits<char>>&)+884)
  native: #06 pc 00000000004878a0  /system/lib64/libart.so (art::Runtime::DumpForSigQuit(std::__1::basic_ostream<char, std::__1::char_traits<char>>&)+188)
  native: #07 pc 0000000000493610  /system/lib64/libart.so (art::SignalCatcher::HandleSigQuit()+1372)
  native: #08 pc 00000000004922e8  /system/lib64/libart.so (art::SignalCatcher::Run(void*)+256)
  native: #09 pc 0000000000082e10  /system/lib64/libc.so (__pthread_start(void*)+36)
  native: #10 pc 0000000000024080  /system/lib64/libc.so (__start_thread+68)
  (no managed stack frames)

"main" prio=5 tid=1 Sleeping
| group="main" sCount=1 dsCount=0 flags=1 obj=0x75771ba0 self=0x7b7b014c00
| sysTid=13709 nice=-10 cgrp=default sched=0/0 handle=0x7c0184d548
| state=S schedstat=( 569303132 16322390 301 ) utm=51 stm=5 core=2 HZ=100
| stack=0x7ff5ac9000-0x7ff5acb000 stackSize=8MB
| held mutexes=
at java.lang.Thread.sleep(Native method)
- sleeping on <0x0808d0f6> (a java.lang.Object)
at java.lang.Thread.sleep(Thread.java:386)
- locked <0x0808d0f6> (a java.lang.Object)
at java.lang.Thread.sleep(Thread.java:327)
at com.yk.silence.customcamera.MainActivity$onCreate$1.onClick(MainActivity.kt:18)
at android.view.View.performClick(View.java:6652)
at android.view.View.performClickInternal(View.java:6624)
at android.view.View.access$3100(View.java:787)
at android.view.View$PerformClick.run(View.java:26213)
at android.os.Handler.handleCallback(Handler.java:891)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:7470)
at java.lang.reflect.Method.invoke(Native method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:524)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:958)

"Jit thread pool worker thread 0" daemon prio=5 tid=2 Native
| group="main" sCount=1 dsCount=0 flags=1 obj=0x156c0030 self=0x7b72033000
| sysTid=13714 nice=9 cgrp=default sched=0/0 handle=0x7b5c7064f0
| state=S schedstat=( 75499990 5454172 203 ) utm=5 stm=2 core=1 HZ=100
| stack=0x7b5c608000-0x7b5c60a000 stackSize=1021KB
| held mutexes=
kernel: (couldn't read /proc/self/task/13714/stack stderr:Permission denied)
native: #00 pc 000000000001f3ec  /system/lib64/libc.so (syscall+28)
native: #01 pc 00000000000dbd94  /system/lib64/libart.so (art::ConditionVariable::WaitHoldingLocks(art::Thread*)+148)
native: #02 pc 00000000004c0fc4  /system/lib64/libart.so (art::ThreadPool::GetTask(art::Thread*)+260)
native: #03 pc 00000000004c052c  /system/lib64/libart.so (art::ThreadPoolWorker::Run()+124)
native: #04 pc 00000000004bffec  /system/lib64/libart.so (art::ThreadPoolWorker::Callback(void*)+148)
native: #05 pc 0000000000082e10  /system/lib64/libc.so (__pthread_start(void*)+36)
native: #06 pc 0000000000024080  /system/lib64/libc.so (__start_thread+68)
(no managed stack frames)

分析:既然我們已經(jīng)拿到了ANR日志文件的內(nèi)容了，那么怎么分析呢？不可能一通亂找吧。這個(gè)是當(dāng)然的，有兩個(gè)可以參考的點(diǎn)，一個(gè)就是我們應(yīng)用程序的包名，另外一個(gè)就是main方法。這里我截取了一部分主要的日志文件，但是也夠了。我們首先看一下"main"方法，并且找一下我們應(yīng)用對(duì)應(yīng)的包名com.yk.silence.customcamera,那么很容易就定位到了at com.yk.silence.customcamera.MainActivity$onCreate$1.onClick(MainActivity.kt:18),這一行，然后我們看一下我們的源碼。在第18行的休眠50S的代碼，所以找對(duì)應(yīng)規(guī)律會(huì)事半功倍。

image.png

最后

好了，這個(gè)就是關(guān)于ANR初探的文章，如果有寫(xiě)的不到位的地方還請(qǐng)大佬不吝賜教。當(dāng)然，如果你有更好的建議歡迎進(jìn)群（493180098）探討。

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