SWT 重启案例分析一

2020-10-16 08:00 程序员Android

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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:

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。

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);

}

}

}

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