Android 从log中学习设备启动过程及代码执行流程

这段时间分析设备概率异常启动慢问题，特此记录。

补充log区分:

一般log里面有sys log、main log、events log、crash log、Rlog，而这些log是怎么实现这些区分？

sys log ---> android.util.Slog (hide类)

main log --> android.util.Log (常用的方式)

events log --> android.util.EventLog

crash log --> com.internal.os.RuntimeInit

radio log-->android.telephony.Rlog(hide类)

(特别注意：内部类LoggingHandler对Clog_e的调用)

进一步了解：

android.util.Log中有如下ID，这也就标明了log的类型：

/** @hide */ public static final int LOG_ID_MAIN = 0;//-- main log

    /** @hide */ public static final int LOG_ID_RADIO = 1;//-- radio log

    /** @hide */ public static final int LOG_ID_EVENTS = 2;//-- events log

    /** @hide */ public static final int LOG_ID_SYSTEM = 3;// -- sys log

    /** @hide */ public static final int LOG_ID_CRASH = 4;//--crash log

其实源头的调用就是：

/** @hide */ public static native int println_native(int bufID,

            int priority, String tag, String msg);

bufID--就是传入上面的ID值

快速解析adb抓log的方式：

adb logcat 默认是main的，所以要抓取log应该如下操作：

adb logcat -b main -b system -b radio -b events -v time

从log中了解开机时间

从events的log中了解开机启动时间：

Android 从log中学习设备启动过程及代码执行流程

解析注意点：

为什么boot_progress_start -->boot_progress_preload_start时间这么长？

关键字："dex2oat"  "dex2oat : dex2oat took"

通过看main log如下：

03-06 10:42:58.283609  479  479 I zygote64: GenerateImage: /system/bin/dex2oat --image=/data/dalvik-cache/arm64/system@framework@boot.art --dex-file=/system/framework/core-oj.jar --dex-file=/system/framework/core-libart.jar --dex-file=/system/framework/conscrypt.jar --dex-file=/system/framework/okhttp.jar --dex-file=/system/framework/bouncycastle.jar --dex-file=/system/framework/apache-xml.jar --dex-file=/system/framework/ext.jar --dex-file=/system/framework/framework.jar --dex-file=/system/framework/telephony-common.jar --dex-file=/system/framework/voip-common.jar --dex-file=/system/framework/ims-common.jar --dex-file=/system/framework/android.hidl.base-V1.0-java.jar --dex-file=/system/framework/android.hidl.manager-V1.0-java.jar --dex-file=/system/framework/framework-oahl-backward-compatibility.jar --dex-file=/system/framework/android.test.base.jar --dex-file=/system/framework/mediatek-common.jar --dex-file=/system/framework/mediatek-framework.jar --dex-file=/system/framework/mediatek-telephony-common.jar --dex-file=/system/framework/mediatek-teleph

03-06 10:43:55.453963  672  672 I dex2oat : dex2oat took 56.741s (81.581s cpu) (threads: 4) arena alloc=16MB (17795744B) java alloc=5MB (6045464B) native alloc=66MB (70099304B) free=17MB (17981080B)

为什么boot_progress_pms_ready -->boot_progress_ams_ready 时间这么长？

关键字：SystemServerTiming 涉及内容在：sys_log

1,826: 03-06 10:44:26.582524  1005  1005 D SystemServerTiming: StartPackageManagerService took to complete: 3768ms

2,172: 03-06 10:45:02.356858  1005  1005 D SystemServerTiming: UpdatePackagesIfNeeded took to complete: 33570ms

补充说明：

1.android.server.SystemServer中对具体方法执行时间有跟踪

Android 从log中学习设备启动过程及代码执行流程

2.使用的是隐藏类

android.util.TimingsTraceLog

进一步解析:

这些信息也可以通过代码获取意义

boot_progress_start

系统进入用户空间，标志着kernel启动完成，本例中可以看出kernel启动耗时30s左右

boot_progress_preload_start

Zygote启动

boot_progress_preload_end

Zygote结束

boot_progress_system_run

SystemServer ready,开始启动Android系统服务，如PMS，APMS等

boot_progress_pms_start

PMS开始扫描安装的应用

boot_progress_pms_system_scan_start

PMS先行扫描/system目录下的安装包

boot_progress_pms_data_scan_start

PMS扫描/data目录下的安装包

boot_progress_pms_scan_end

PMS扫描结束

boot_progress_pms_ready

PMS就绪

boot_progress_ams_ready

AMS就绪

boot_progress_enable_screen

AMS启动完成后开始激活屏幕，从此以后屏幕才能响应用户的触摸，它在WindowManagerService发出退出开机动画的时间节点之前，而真正退出开机动画还会花费少许时间，具体依赖animation zip 包中的desc.txt。wm_boot_animation_done才是用户感知到的动画结束时间节点

sf_stop_bootanim

SF设置service.bootanim.exit属性值为1，标志系统要结束开机动画了，可以用来跟踪开机动画结尾部分消耗的时间

wm_boot_animation_done

开机动画结束，这一步用户能直观感受到开机结束

。可以用此来衡量是否开机完成--7.0以上出现

注意java层使用的是EventLog.java

EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_START,

参考学习：

http://www.mamicode.com/info-detail-1789654.html

https://blog.51cto.com/ticktick/1660996

https://blog.csdn.net/zhangbijun1230/article/details/80562616

https://blog.csdn.net/poolwater/article/details/51839402

https://blog.csdn.net/a04081122/article/details/52314709

从log中学习代码执行流程：

E SystemServiceRegistry: No service published for: dropbox

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry: android.os.ServiceManager$ServiceNotFoundException: No service published for: dropbox

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.os.ServiceManager.getServiceOrThrow(ServiceManager.java:143)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.app.SystemServiceRegistry$19.createService(SystemServiceRegistry.java:355)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.app.SystemServiceRegistry$19.createService(SystemServiceRegistry.java:352)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.app.SystemServiceRegistry$CachedServiceFetcher.getService(SystemServiceRegistry.java:1137)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.app.SystemServiceRegistry.getSystemService(SystemServiceRegistry.java:1053)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.app.ContextImpl.getSystemService(ContextImpl.java:1726)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at com.android.server.am.ActivityManagerService.logStrictModeViolationToDropBox(ActivityManagerService.java:15884)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at com.android.server.am.ActivityManagerService.handleApplicationStrictModeViolation(ActivityManagerService.java:15843)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.os.StrictMode.handleApplicationStrictModeViolation(StrictMode.java:1772)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.os.StrictMode.access$1400(StrictMode.java:141)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.os.StrictMode$AndroidBlockGuardPolicy.onThreadPolicyViolation(StrictMode.java:1702)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.os.StrictMode$AndroidBlockGuardPolicy.lambda$handleViolationWithTimingAttempt$0(StrictMode.java:1621)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.os.-$$Lambda$StrictMode$AndroidBlockGuardPolicy$9nBulCQKaMajrWr41SB7f7YRT1I.run(Unknown Source:6)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.os.Handler.handleCallback(Handler.java:873)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.os.Handler.dispatchMessage(Handler.java:99)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.os.Looper.loop(Looper.java:193)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at android.os.HandlerThread.run(HandlerThread.java:65)

03-01 10:00:48.942572  973  1039 E SystemServiceRegistry:  at com.android.server.ServiceThread.run(ServiceThread.java:44)

展示常规Context调用服务的流程--MTK 9.0系统

展示mContext.getSystemService(Context.DROPBOX_SERVICE)调用服务的流程：

一、

DropBoxManager dbox = (DropBoxManager)        mContext.getSystemService(Context.DROPBOX_SERVICE);

二、

android.app.ContextImpl.getSystemService(ContextImpl.java:1726)

三、

android.app.SystemServiceRegistry.getSystemService(SystemServiceRegistry.java:1053)

注：

这里面有一抽象类，运行的非常漂亮

public static abstract class CachedServiceFetcher<T> implements ServiceFetcher<T> {

}

四、

android.app.SystemServiceRegistry$CachedServiceFetcher.getService(SystemServiceRegistry.java:1137)

五、

android.app.SystemServiceRegistry$19.createService(SystemServiceRegistry.java:352)

六、

android.os.ServiceManager.getServiceOrThrow(ServiceManager.java:143)

Tips:

想了解某一个方法是怎么调用的，可以通过：

丢throw 异常来处理。

public static IBinder getServiceOrThrow(String name) throws ServiceNotFoundException {

        final IBinder binder = getService(name);

        if (binder != null) {

            return binder;

        } else {

            throw new ServiceNotFoundException(name);

        }

    }