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_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

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.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);
 
                     }
 
                 }
 
             }

参考文献：

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

友情推荐：

Android 开发干货集锦

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原文地址：https://blog.csdn.net/wjky2014/article/details/132014005