MTK system_server 卡死导致手机重启案例分析

和你一起终身学习，这里是程序员Android

经典好文推荐，通过阅读本文，您将收获以下知识点:

一、MTK AEE Log分析工具
二、AEE Log分析流程
三、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：

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。

使用解析db.fatal.02.SWT.dbg

AEE Log 解析出来的文件

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_watchdogCurrent Executing Process: 
system_serverTrigger time:[2019-03-14 14:00:03.711844] pid:1029Backtrace: 
Process: system_server
Subject: Blocked in handler on ActivityManager (ActivityManager)
Build: ACE/AS0618/AS0618:8.1.0/O11019/1548123508:user/release-keys

3.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$** *** *** *** *** *** *** *** Fatal *** *** *** *** *** *** *** **$

Log 分析大致过程截图

完整 log 请在公众号上获取

三、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。

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

2.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。

3.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.Stubstatic 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.Stubsynchronized (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.StubcleanupAppInLaunchingProvidersLocked(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.Stubif (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);}}}

参考文献：

【腾讯文档】Android Framework 知识库
https://docs.qq.com/doc/DSXBmSG9VbEROUXF5

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