记一次解决ANR问题的笔记

记录一次解决ANR问题的笔记：

起因：

在项目提测之后，QA同学提了一个ANR的bug，然后按照她的步骤走了一遍，发现没有复现，所以怀疑是机型或者是账号的问题，于是把QA同学的手机借来又试了一遍，还是没有复现，于是怀疑跟账号有关系（APP需要登录），于是把她的账号也要过来又走了一遍，果然多次来回点击，若干次重复操作后就ANR了，既然出现了ANR，就来排查trace文件吧

排查：

1、先来看看AS中的Log日志：

ActivityManager: ANR in com.xxxx.demo (ANR in com.xxxx.demo/.activity.MainActivity)   
PID: 32265 

Reason: Input dispatching timed out (Waiting to send non-key event because the touched window has not finished processing certain input events that were delivered to it over 500.0ms ago. waitqueue length = 27, head.seq = 2631206, Wait queue head age: 8508.5ms.)

Load: 47.49 / 46.52 / 46.17 CPU usage from 3742ms to -4031ms ago (2018-05-03 17:00:43.398 to 2018-05-03 17:00:51.171):
 ....其他....                                              

当Activity处于前台，APP在5秒内没有响应点击触摸事件时，就会产生ANR，通过LOG可以知道我们就是这种原因导致的ANR，那么具体是哪里的引起的这个问题呢？我们接着去trace文件中找答案。

2、导出trace.txt：

在AS中将下面的控制台切换到Terminal控制台，输入下面的命令：

adb pull /data/anr/traces.txt /document/trace

上述命令是将/data/anr目录下的trace文件导出到/document/trace目录下，回车，控制台输出：

/data/anr/traces.txt: 1 file pulled. 16.4 MB/s (312500 bytes in 0.018s)

说明导出成功，去相应目录下找到我们的traces.txt文件。

3、查看trace文件：

----- pid 8939 at 2018-05-03 17:18:51 -----
Cmd line: com.xxxx.demo //包名 及ANR发生时间
Build fingerprint: 'HUAWEI/ALP-AL00/HWALP:8.0.0/HUAWEIALP-AL00/128(SP2C00):user/release-keys'
ABI: 'arm64'
Build type: optimized
Zygote loaded classes=4756 post zygote classes=1856
Intern table: 47739 strong; 137 weak
JNI: CheckJNI is off; globals=7185 (plus 37 weak)

.....一些堆栈信息.....

"main" prio=5 tid=1 Native
  | group="main" sCount=1 dsCount=0 flags=1 obj=0x72f1bb10 self=0x793e0a3a00
  | sysTid=8939 nice=-10 cgrp=default sched=0/0 handle=0x7942f6a9b0
  | state=S schedstat=( 6206740125 206669232 6096 ) utm=562 stm=57 core=0 HZ=100
  | stack=0x7fd32ea000-0x7fd32ec000 stackSize=8MB
  | held mutexes=
  kernel: __switch_to+0xac/0xc0
  kernel: futex_wait_queue_me+0x100/0x1a0
  kernel: futex_wait+0x104/0x23c
  kernel: do_futex+0x16c/0x534
  kernel: SyS_futex+0x128/0x1bc
  kernel: __sys_trace_return+0x0/0x4
  native: #00 pc 000000000001da2c  /system/lib64/libc.so (syscall+28)
  native: #01 pc 0000000000066040  /system/lib64/libc.so (pthread_cond_wait+96)
  native: #02 pc 000000000004d5f8  /system/lib64/libhwui.so (???)
  native: #03 pc 00000000002c88bc  /system/framework/arm64/boot-framework.oat (Java_android_view_ThreadedRenderer_nSyncAndDrawFrame__J_3JI+188)
  at android.view.ThreadedRenderer.nSyncAndDrawFrame(Native method)
  at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:829)
  at android.view.ViewRootImpl.draw(ViewRootImpl.java:3178)
  at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2976)
  at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2505)
  at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1512)
  at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7218)
  at android.view.Choreographer$CallbackRecord.run(Choreographer.java:981)
  at android.view.Choreographer.doCallbacks(Choreographer.java:790)
  at android.view.Choreographer.doFrame(Choreographer.java:721)
  at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:967)
  at android.os.Handler.handleCallback(Handler.java:808)
  at android.os.Handler.dispatchMessage(Handler.java:101)
  at android.os.Looper.loop(Looper.java:166)
  at android.app.ActivityThread.main(ActivityThread.java:7425)
  at java.lang.reflect.Method.invoke(Native method)
  at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921)

重点看下面这几行：

android.view.ThreadedRenderer.draw(ThreadedRenderer.java:829)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:3178)
at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2976)

OK,虽然没有具体定位到哪一行代码，但是根据ANR出现的时机以及复现条件大概推断出是哪里出了问题，最后发现是自定义View的onDraw()中漏判了一个条件导致无限循环了，OK，到这里就把问题解决了，把这个问题记录下来方便以后来查询，也提醒自己要再细心一些~

相关网址：
[1]：https://developer.android.com/topic/performance/vitals/anr