Android log常用分析方法

1. ANR

应用在一定时间内由于主线程阻塞而没做出相应，系统将会杀死这个进程并且dump栈信息到/data/anr目录中。检查ANR log需要两种类型的log，需要event log、logcat log和/data/anr下的log。这两种log主要是为了找出发生ANR的进程号和发生ARN时的类信息，拿网上的例子做个说明:

如果是event log，搜索 “am_anr” 关键字：

10-01 18:12:49.599  4600  4614 I am_anr  : [0,29761,com.google.android.youtube,953695941,executing service com.google.android.youtube/com.google.android.apps.youtube.app.offline.transfer.OfflineTransferService]
10-01 18:14:10.211  4600  4614 I am_anr  : [0,30363,com.google.android.apps.plus,953728580,executing service com.google.android.apps.plus/com.google.android.apps.photos.service.PhotosService]

如果是logcat log，搜索关键字“ANR”:

10-01 18:13:11.984  4600  4614 E ActivityManager: ANR in com.google.android.youtube
10-01 18:14:31.720  4600  4614 E ActivityManager: ANR in com.google.android.apps.plus
10-01 18:14:31.720  4600  4614 E ActivityManager: PID: 30363
10-01 18:14:31.720  4600  4614 E ActivityManager: Reason: executing service com.google.android.apps.plus/com.google.android.apps.photos.service.PhotosService
10-01 18:14:31.720  4600  4614 E ActivityManager: Load: 35.27 / 23.9 / 16.18
10-01 18:14:31.720  4600  4614 E ActivityManager: CPU usage from 16ms to 21868ms later:
10-01 18:14:31.720  4600  4614 E ActivityManager:   74% 3361/mm-qcamera-daemon: 62% user + 12% kernel / faults: 15276 minor 10 major
10-01 18:14:31.720  4600  4614 E ActivityManager:   41% 4600/system_server: 18% user + 23% kernel / faults: 18597 minor 309 major
10-01 18:14:31.720  4600  4614 E ActivityManager:   32% 27420/com.google.android.GoogleCamera: 24% user + 7.8% kernel / faults: 48374 minor 338 major
10-01 18:14:31.720  4600  4614 E ActivityManager:   16% 130/kswapd0: 0% user + 16% kernel
10-01 18:14:31.720  4600  4614 E ActivityManager:   15% 283/mmcqd/0: 0% user + 15% kernel
...
10-01 18:14:31.720  4600  4614 E ActivityManager:   0.1% 27248/irq/503-synapti: 0%
10-01 18:14:31.721  4600  4614 I ActivityManager: Killing 30363:com.google.android.

通过这两种log都能看出进程 30363 在执行com.google.android.apps.plus/com.google.android.apps.photos.service.PhotosService 时发生了ANR，event log更加简明，不过需要对着EventLogTags.logtags文件看，logcat更加易懂些。

接着需要看/data/anr下traces.txt文件的栈信息了，看栈信息的主要注意事项就是要确保该traces.txt是对应ANR的文件，因为系统可能发生了多次ARN，/data/anr路径下
可能有多个文件，接着我们要找到发生ANR进程的栈信息：

----- pid 30363 at 2015-10-01 18:14:11 -----
Cmd line: com.google.android.apps.plus
Build fingerprint: 'google/angler/angler:6.0/MDA89D/2294819:userdebug/dev-keys'
ABI: 'arm'
Build type: optimized
Zygote loaded classes=3978 post zygote classes=27
Intern table: 45068 strong; 21 weak
JNI: CheckJNI is off; globals=283 (plus 360 weak)
Libraries: /system/lib/libandroid.so /system/lib/libcompiler_rt.so /system/lib/libjavacrypto.so /system/lib/libjnigraphics.so /system/lib/libmedia_jni.so /system/lib/libwebviewchromium_loader.so libjavacore.so (7)
Heap: 29% free, 21MB/30MB; 32251 objects
Dumping cumulative Gc timings
Total number of allocations 32251
Total bytes allocated 21MB
Total bytes freed 0B
Free memory 9MB
Free memory until GC 9MB
Free memory until OOME 490MB
Total memory 30MB
Max memory 512MB
Zygote space size 1260KB
Total mutator paused time: 0
Total time waiting for GC to complete: 0
Total GC count: 0
Total GC time: 0
Total blocking GC count: 0
Total blocking GC time: 0

suspend all histogram:  Sum: 119.728ms 99% C.I. 0.010ms-107.765ms Avg: 5.442ms Max: 119.562ms
DALVIK THREADS (12):
"Signal Catcher" daemon prio=5 tid=2 Runnable
  | group="system" sCount=0 dsCount=0 obj=0x12c400a0 self=0xef460000
  | sysTid=30368 nice=0 cgrp=default sched=0/0 handle=0xf4a69930
  | state=R schedstat=( 9021773 5500523 26 ) utm=0 stm=0 core=1 HZ=100
  | stack=0xf496d000-0xf496f000 stackSize=1014KB
  | held mutexes= "mutator lock"(shared held)
  native: #00 pc 0035a217  /system/lib/libart.so (art::DumpNativeStack(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, int, char const*, art::ArtMethod*, void*)+126)
  native: #01 pc 0033b03b  /system/lib/libart.so (art::Thread::Dump(std::__1::basic_ostream<char, std::__1::char_traits<char> >&) const+138)
  native: #02 pc 00344701  /system/lib/libart.so (art::DumpCheckpoint::Run(art::Thread*)+424)
  native: #03 pc 00345265  /system/lib/libart.so (art::ThreadList::RunCheckpoint(art::Closure*)+200)
  native: #04 pc 00345769  /system/lib/libart.so (art::ThreadList::Dump(std::__1::basic_ostream<char, std::__1::char_traits<char> >&)+124)
  native: #05 pc 00345e51  /system/lib/libart.so (art::ThreadList::DumpForSigQuit(std::__1::basic_ostream<char, std::__1::char_traits<char> >&)+312)
  native: #06 pc 0031f829  /system/lib/libart.so (art::Runtime::DumpForSigQuit(std::__1::basic_ostream<char, std::__1::char_traits<char> >&)+68)
  native: #07 pc 00326831  /system/lib/libart.so (art::SignalCatcher::HandleSigQuit()+896)
  native: #08 pc 003270a1  /system/lib/libart.so (art::SignalCatcher::Run(void*)+324)
  native: #09 pc 0003f813  /system/lib/libc.so (__pthread_start(void*)+30)
  native: #10 pc 00019f75  /system/lib/libc.so (__start_thread+6)
  (no managed stack frames)

"main" prio=5 tid=1 Suspended
  | group="main" sCount=1 dsCount=0 obj=0x747552a0 self=0xf5376500
  | sysTid=30363 nice=0 cgrp=default sched=0/0 handle=0xf74feb34
  | state=S schedstat=( 331107086 164153349 851 ) utm=6 stm=27 core=3 HZ=100
  | stack=0xff00f000-0xff011000 stackSize=8MB
  | held mutexes=
  kernel: __switch_to+0x7c/0x88
  kernel: futex_wait_queue_me+0xd4/0x130
  kernel: futex_wait+0xf0/0x1f4
  kernel: do_futex+0xcc/0x8f4
  kernel: compat_SyS_futex+0xd0/0x14c
  kernel: cpu_switch_to+0x48/0x4c
  native: #00 pc 000175e8  /system/lib/libc.so (syscall+28)
  native: #01 pc 000f5ced  /system/lib/libart.so (art::ConditionVariable::Wait(art::Thread*)+80)
  native: #02 pc 00335353  /system/lib/libart.so (art::Thread::FullSuspendCheck()+838)
  native: #03 pc 0011d3a7  /system/lib/libart.so (art::ClassLinker::LoadClassMembers(art::Thread*, art::DexFile const&, unsigned char const*, art::Handle<art::mirror::Class>, art::OatFile::OatClass const*)+746)
  native: #04 pc 0011d81d  /system/lib/libart.so (art::ClassLinker::LoadClass(art::Thread*, art::DexFile const&, art::DexFile::ClassDef const&, art::Handle<art::mirror::Class>)+88)
  native: #05 pc 00132059  /system/lib/libart.so (art::ClassLinker::DefineClass(art::Thread*, char const*, unsigned int, art::Handle<art::mirror::ClassLoader>, art::DexFile const&, art::DexFile::ClassDef const&)+320)
  native: #06 pc 001326c1  /system/lib/libart.so (art::ClassLinker::FindClassInPathClassLoader(art::ScopedObjectAccessAlreadyRunnable&, art::Thread*, char const*, unsigned int, art::Handle<art::mirror::ClassLoader>, art::mirror::Class**)+688)
  native: #07 pc 002cb1a1  /system/lib/libart.so (art::VMClassLoader_findLoadedClass(_JNIEnv*, _jclass*, _jobject*, _jstring*)+264)
  native: #08 pc 002847fd  /data/dalvik-cache/arm/system@framework@boot.oat (Java_java_lang_VMClassLoader_findLoadedClass__Ljava_lang_ClassLoader_2Ljava_lang_String_2+112)
  at java.lang.VMClassLoader.findLoadedClass!(Native method)
  at java.lang.ClassLoader.findLoadedClass(ClassLoader.java:362)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:499)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
  at android.app.ActivityThread.installProvider(ActivityThread.java:5141)
  at android.app.ActivityThread.installContentProviders(ActivityThread.java:4748)
  at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4688)
  at android.app.ActivityThread.-wrap1(ActivityThread.java:-1)
  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1405)
  at android.os.Handler.dispatchMessage(Handler.java:102)
  at android.os.Looper.loop(Looper.java:148)
  at android.app.ActivityThread.main(ActivityThread.java:5417)
  at java.lang.reflect.Method.invoke!(Native method)
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

  ...
  Stacks for other threads in this process follow
  ...

2. 死锁

对于普通应用，死锁常常会以ANR的形式出现，但如果是对于system server进程，看门狗会咬死system server进程，从而导致系统重启，而且这种情况会有类似 “WATCHDOG KILLING SYSTEM PROCESS” 这种log出现。

检查这种问题，需要检查VM的log，这时logcat就不行了，抓 dumpstate 的log吧，然后搜索“Blocked”和“held by thread”关键字，然后一点一点细致的检查，如下面网上的log：

"Binder_B" prio=5 tid=73 Blocked
  | group="main" sCount=1 dsCount=0 obj=0x13faa0a0 self=0x95e24800
  | sysTid=2016 nice=0 cgrp=default sched=0/0 handle=0x8b68d930
  | state=S schedstat=( 9351576559 4141431119 16920 ) utm=819 stm=116 core=1 HZ=100
  | stack=0x8b591000-0x8b593000 stackSize=1014KB
  | held mutexes=
  at com.android.server.pm.UserManagerService.exists(UserManagerService.java:387)
  - waiting to lock <0x025f9b02> (a android.util.ArrayMap) **held by thread 20**
  at com.android.server.pm.PackageManagerService.getApplicationInfo(PackageManagerService.java:2848)
  at com.android.server.AppOpsService.getOpsRawLocked(AppOpsService.java:881)
  at com.android.server.AppOpsService.getOpsLocked(AppOpsService.java:856)
  at com.android.server.AppOpsService.noteOperationUnchecked(AppOpsService.java:719)
  - locked <0x0231885a> (a com.android.server.AppOpsService)
  at com.android.server.AppOpsService.noteOperation(AppOpsService.java:713)
  at com.android.server.AppOpsService$2.getMountMode(AppOpsService.java:260)
  at com.android.server.MountService$MountServiceInternalImpl.getExternalStorageMountMode(MountService.java:3416)
  at com.android.server.am.ActivityManagerService.startProcessLocked(ActivityManagerService.java:3228)
  at com.android.server.am.ActivityManagerService.startProcessLocked(ActivityManagerService.java:3170)
  at com.android.server.am.ActivityManagerService.startProcessLocked(ActivityManagerService.java:3059)
  at com.android.server.am.BroadcastQueue.processNextBroadcast(BroadcastQueue.java:1070)
  - locked <0x044d166f> (a com.android.server.am.ActivityManagerService)
  at com.android.server.am.ActivityManagerService.finishReceiver(ActivityManagerService.java:16950)
  at android.app.ActivityManagerNative.onTransact(ActivityManagerNative.java:494)
  at com.android.server.am.ActivityManagerService.onTransact(ActivityManagerService.java:2432)
  at android.os.Binder.execTransact(Binder.java:453)
...
  "PackageManager" prio=5 tid=20 Blocked
  | group="main" sCount=1 dsCount=0 obj=0x1304f4a0 self=0xa7f43900
  | sysTid=1300 nice=10 cgrp=bg_non_interactive sched=0/0 handle=0x9fcf9930
  | state=S schedstat=( 26190141996 13612154802 44357 ) utm=2410 stm=209 core=2 HZ=100
  | stack=0x9fbf7000-0x9fbf9000 stackSize=1038KB
  | held mutexes=
  at com.android.server.AppOpsService.noteOperationUnchecked(AppOpsService.java:718)
  - waiting to lock <0x0231885a> (a com.android.server.AppOpsService) **held by thread 73**
  at com.android.server.AppOpsService.noteOperation(AppOpsService.java:713)
  at com.android.server.AppOpsService$2.getMountMode(AppOpsService.java:260)
  at com.android.server.AppOpsService$2.hasExternalStorage(AppOpsService.java:273)
  at com.android.server.MountService$MountServiceInternalImpl.hasExternalStorage(MountService.java:3431)
  at com.android.server.MountService.getVolumeList(MountService.java:2609)
  at android.os.storage.StorageManager.getVolumeList(StorageManager.java:880)
  at android.os.Environment$UserEnvironment.getExternalDirs(Environment.java:83)
  at android.os.Environment.isExternalStorageEmulated(Environment.java:708)
  at com.android.server.pm.PackageManagerService.isExternalMediaAvailable(PackageManagerService.java:9327)
  at com.android.server.pm.PackageManagerService.startCleaningPackages(PackageManagerService.java:9367)
  - locked <0x025f9b02> (a android.util.ArrayMap)
  at com.android.server.pm.PackageManagerService$PackageHandler.doHandleMessage(PackageManagerService.java:1320)
  at com.android.server.pm.PackageManagerService$PackageHandler.handleMessage(PackageManagerService.java:1122)
  at android.os.Handler.dispatchMessage(Handler.java:102)
  at android.os.Looper.loop(Looper.java:148)
  at android.os.HandlerThread.run(HandlerThread.java:61)
  at com.android.server.ServiceThread.run(ServiceThread.java:46)

线程73要的锁被线程 20 持有，而线程 20 申请的锁被线程 73 持有。

3. Activities

看焦点activity，关键字 am_focused_activity

进程启动历史，关键字 Start proc

确认设备是否抖动，关键字 am_proc_died 和 am_proc_start，检查是否在短时间内出现了大量的这样的log。

参考：Android log常用分析方法：https://blog.csdn.net/moonshine2016/article/details/55669408