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SWT 重启案例分析（一）

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Android 干货分享

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阅读五分钟，每日十点，和您一起终身学习，这里是程序员Android

本篇文章主要介绍 Android 开发中的部分知识点，通过阅读本篇文章，您将收获以下内容:

1.MTK AEE Log分析工具
2.AEE Log分析流程
3.system_server 卡死案例分析及解决

本文主要针对 Exception Type: system_server_watchdog , system_server卡死找出的分析以及解决方案。

一、MTK AEE Log分析工具

MTK AEE Log 获取方式：

关注微信公众号： 程序员Android
回复 aee 即可获取解析重启db log的工具。

二、AEE Log分析流程

1. 使用AEE 工具解析 dbg 文件。

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2.分析解析出来的exp_main等文件

exp_main 文件会记录发生重启时候的 log 打印信息。

部分重启异常 Log信息如下：

$** *** *** *** *** *** *** *** Fatal *** *** *** *** *** *** *** **$
Build Info: 'alps-mp-o1.mp7:alps-mp-o1.mp7:mt6765:S01,ACE/AS0618/AS0618:8.1.0/O11019/1548123508:user/release-keys'
Flavor Info: 'None'
Exception Log Time:[Thu Mar 14 14:00:03 CST 2019] [38684.729626]

Exception Class: SWT
Exception Type: system_server_watchdog

Current Executing Process: 
system_server


Trigger time:[2019-03-14 14:00:03.711844] pid:1029

Backtrace: 
Process: system_server
Subject: Blocked in handler on ActivityManager (ActivityManager)
Build: ACE/AS0618/AS0618:8.1.0/O11019/1548123508:user/release-keys

exp_main 文件解析
从开头的Log总体信息概览，我们可以看到 发生重启的时间、类型，触发重启的进程以及PID、系统Blocked 的地方。

结合exp_main以及 trace分析重启 Log
Log分析如下：

// 1.重启触发时间，以及PID 
Trigger time:[2019-03-14 14:00:03.711844] pid:1029
// 2.Blocked 的进程
Backtrace: 
Process: system_server
Subject: Blocked in handler on ActivityManager (ActivityManager)
// 3.根据PID 查看Trace信息
----- pid 1029 at 2019-03-14 13:59:58 -----
Cmd line: system_server

... ...
// 4.根据Backtrace 查看Blocked的信息
"ActivityManager" prio=5 tid=11 Blocked

... ...
// 5.tid=11 等待 tid=106的线程释放资源锁
  - waiting to lock <0x090691f3> (a android.util.ArrayMap) held by thread 106  
... ...

// 6.查看tid = 106 持锁情况
"backup" prio=5 tid=106 Waiting
... ... 

  at java.lang.Object.wait(Native method)
  - waiting on <0x06a44c62> (a com.android.server.am.ContentProviderRecord)
// 7.死锁卡住的地方
  at com.android.server.am.ActivityManagerService.getContentProviderImpl(ActivityManagerService.java:12127)
  - locked <0x06a44c62> (a com.android.server.am.ContentProviderRecord)
  
  ...  ...

"Binder:1029_8" prio=5 tid=107 Blocked
// 8.log中  tid=107 被 106 Blocked 进一步问题的加重
  at com.android.server.notification.RankingHelper.getRecord(RankingHelper.java:258)
  - waiting to lock <0x090691f3> (a android.util.ArrayMap) held by thread 106
  
$** *** *** *** *** *** *** *** Fatal *** *** *** *** *** *** *** **$

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完整 log 请在公众号上获取

3.system_server 卡死案例分析及解决

通过 Log 找到卡死原因后，解决此问题。
需要修改ActivityManagerService类。

代码路径如下：alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java

解决思路：
避免 provider 长时间持锁触发MTK 60s 的SWT 重启机制，设置超时时间，超过时间就要释放资源锁，避免发生此问题。

diff 修改方案如下：

--- a/[alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=d5e2e1411f3698a829e997d402c7482ec277fa8c;hb=d5e2e1411f3698a829e997d402c7482ec277fa8c)

+++ b/[alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=03208f78a2bf3167b4f0790019326e3939cc5444;hb=03208f78a2bf3167b4f0790019326e3939cc5444)

@@ [-545,7](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=d5e2e1411f3698a829e997d402c7482ec277fa8c;hb=d5e2e1411f3698a829e997d402c7482ec277fa8c#l545) [+545,9](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=03208f78a2bf3167b4f0790019326e3939cc5444;hb=03208f78a2bf3167b4f0790019326e3939cc5444#l545) @@?public?class?ActivityManagerService?extends?IActivityManager.Stub

?????//?How?long?we?wait?for?an?attached?process?to?publish?its?content?providers

?????//?before?we?decide?it?must?be?hung.

?????static?final?int?CONTENT_PROVIDER_PUBLISH_TIMEOUT?=?10*1000;

-

+????//?How?long?we?wait?for?provider?to?be?notify?before?we?decide?it?may?be?hung.

+????static?final?int?CONTENT_PROVIDER_WAIT_TIMEOUT?=?20*1000;

+???????

?????//?How?long?we?wait?for?a?launched?process?to?attach?to?the?activity?manager

?????//?before?we?decide?it's?never?going?to?come?up?for?real,?when?the?process?was

?????//?started?with?a?wrapper?for?instrumentation?(such?as?Valgrind)?because?it

@@ [-1745,6](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=d5e2e1411f3698a829e997d402c7482ec277fa8c;hb=d5e2e1411f3698a829e997d402c7482ec277fa8c#l1745) [+1747,7](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=03208f78a2bf3167b4f0790019326e3939cc5444;hb=03208f78a2bf3167b4f0790019326e3939cc5444#l1747) @@?public?class?ActivityManagerService?extends?IActivityManager.Stub

?????static?final?int?PUSH_TEMP_WHITELIST_UI_MSG?=?68;

?????static?final?int?SERVICE_FOREGROUND_CRASH_MSG?=?69;

?????static?final?int?DISPATCH_OOM_ADJ_OBSERVER_MSG?=?70;

+????????static?final?int?CONTENT_PROVIDER_WAIT_TIMEOUT_MSG?=?71;

?????static?final?int?START_USER_SWITCH_FG_MSG?=?712;

?????static?final?int?NOTIFY_VR_KEYGUARD_MSG?=?74;

@@ [-2108,6](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=d5e2e1411f3698a829e997d402c7482ec277fa8c;hb=d5e2e1411f3698a829e997d402c7482ec277fa8c#l2108) [+2111,12](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=03208f78a2bf3167b4f0790019326e3939cc5444;hb=03208f78a2bf3167b4f0790019326e3939cc5444#l2111) @@?public?class?ActivityManagerService?extends?IActivityManager.Stub

?????????????????synchronized?(ActivityManagerService.this)?{

?????????????????????mActivityStarter.doPendingActivityLaunchesLocked(true);

?????????????????}

+????????????}?break;

+???????????????????????case?CONTENT_PROVIDER_WAIT_TIMEOUT_MSG:?{

+????????????????ContentProviderRecord?cpr?=?(ContentProviderRecord)msg.obj;

+????????????????synchronized?(ActivityManagerService.this)?{

+????????????????????processContentProviderWaitTimedOutLocked(cpr);

+????????????????}

?????????????}?break;

?????????????case?KILL_APPLICATION_MSG:?{

?????????????????synchronized?(ActivityManagerService.this)?{

@@ [-7029,7](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=d5e2e1411f3698a829e997d402c7482ec277fa8c;hb=d5e2e1411f3698a829e997d402c7482ec277fa8c#l7029) [+7038,31](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=03208f78a2bf3167b4f0790019326e3939cc5444;hb=03208f78a2bf3167b4f0790019326e3939cc5444#l7038) @@?public?class?ActivityManagerService?extends?IActivityManager.Stub

?????????cleanupAppInLaunchingProvidersLocked(app,?true);

?????????removeProcessLocked(app,?false,?true,?"timeout?publishing?content?providers");

?????}

+???????

+????@GuardedBy("this")

+????private?final?void?processContentProviderWaitTimedOutLocked(ContentProviderRecord?cpr)?{

+????????try?{

+????????????if?(mLaunchingProviders.contains(cpr))?{

+????????????????if?(DEBUG_MU)?Slog.v(TAG_MU,

+????????????????????"Remove?from?mLaunchingProviders,?"?+?cpr

+????????????????????+?"?launchingApp="?+?cpr.launchingApp);

+????????????????mLaunchingProviders.remove(cpr);

+????????????}

+????????????if?(DEBUG_MU)?Slog.v(TAG_MU,

+????????????????"RemoveMessages?CONTENT_PROVIDER_WAIT_TIMEOUT_MSG,?"?+?cpr

+????????????????+?"?launchingApp="?+?cpr.launchingApp);

+????????????mHandler.removeMessages(CONTENT_PROVIDER_WAIT_TIMEOUT_MSG,?cpr);

+????????????synchronized?(cpr)?{

+????????????????cpr.notifyAll();

+????????????????cpr.launchingApp?=?null;

+????????????}

+????????}?catch?(Exception?e)?{

+????????????if?(DEBUG_MU)?Slog.v(TAG_MU,

+????????????????"processContentProviderWaitTimedOutLocked?exception,?"?+?e);

+????????}

+????}

+???????

?????private?final?void?processStartTimedOutLocked(ProcessRecord?app)?{

?????????final?int?pid?=?app.pid;

?????????boolean?gone?=?false;

@@ [-12124,11](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=d5e2e1411f3698a829e997d402c7482ec277fa8c;hb=d5e2e1411f3698a829e997d402c7482ec277fa8c#l12124) [+12157,33](http://192.168.11.104/gitweb/?p=alps-mp-o1.mp1-V1.git;a=blob;f=alps/frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java;h=03208f78a2bf3167b4f0790019326e3939cc5444;hb=03208f78a2bf3167b4f0790019326e3939cc5444#l12157) @@?public?class?ActivityManagerService?extends?IActivityManager.Stub

?????????????????????if?(conn?!=?null)?{

?????????????????????????conn.waiting?=?true;

?????????????????????}

+???????????????????????????????????????//?add?20s?wait?timeout，avoid?

+????????????????????if?(!mHandler.hasMessages(CONTENT_PROVIDER_WAIT_TIMEOUT_MSG,?cpr))?{

+????????????????????????if?(DEBUG_MU)?Slog.v(TAG_MU,

+????????????????????????????"SendMessageDelayed?CONTENT_PROVIDER_WAIT_TIMEOUT_MSG,?"?+?cpr

+????????????????????????????+?"?launchingApp="?+?cpr.launchingApp);

+????????????????????????Message?msg?=?mHandler.obtainMessage(CONTENT_PROVIDER_WAIT_TIMEOUT_MSG);

+????????????????????????msg.obj?=?cpr;

+????????????????????????mHandler.sendMessageDelayed(msg,?CONTENT_PROVIDER_WAIT_TIMEOUT);

+????????????????????}?else?{

+????????????????????????if?(DEBUG_MU)?Slog.v(TAG_MU,

+????????????????????????????"There?is?another?waiting?to?start?provider?"?+?cpr

+????????????????????????????+?"?launchingApp="?+?cpr.launchingApp

+????????????????????????????+?",?not?send?CONTENT_PROVIDER_WAIT_TIMEOUT_MSG?again");

+????????????????????}

+???????????????????????????????????????

?????????????????????cpr.wait();

?????????????????}?catch?(InterruptedException?ex)?{

?????????????????}?finally?{

?????????????????????if?(conn?!=?null)?{

?????????????????????????conn.waiting?=?false;

+????????????????????}

+???????????????????????????????????????//?remove?wait?time?out?message

+????????????????????if?(mHandler.hasMessages(CONTENT_PROVIDER_WAIT_TIMEOUT_MSG,?cpr))?{

+????????????????????????if?(DEBUG_MU)?Slog.v(TAG_MU,

+????????????????????????????"After?wait?removeMessages?CONTENT_PROVIDER_WAIT_TIMEOUT_MSG,?"

+????????????????????????????+?cpr?+?"?launchingApp="?+?cpr.launchingApp);

+????????????????????????????mHandler.removeMessages(CONTENT_PROVIDER_WAIT_TIMEOUT_MSG,?cpr);

?????????????????????}

?????????????????}

?????????????}

至此，本篇已结束，如有不对的地方，欢迎您的建议与指正。同时期待您的关注，感谢您的阅读，谢谢！

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SWT 重启案例分析（一）

原文：https://www.cnblogs.com/wangjie1990/p/11326930.html
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