目录
引言
Android系统服务启动顺序
zygote fork SystemServer 进程
SystemServer启动流程
1、SystemServer.main()
2、SystemServer.run()
3、初始化系统上下文
4、创建系统服务管理
5、启动系统各种服务
总结
引言
开机启动时 PowerManagerService 调用 AudioService 音频接口可能会导致 JE 崩溃，进而 system_server 崩溃。
分析：应该和系统服务SystemServer启动的顺序有关
Android系统服务启动顺序
Android整体启动流程概括为：启动BootLoader->加载系统内核->启动Init进程->启动Zygote进程->启动Runtime进程->启动本地服务->启动Home Launcher
SystemServer 服务进程是 Android 系统 Java 层框架的核心，它维护着 Android 系统的 核心服务，比如：ActivityManagerService、WindowManagerService、PackageManagerService 等，是 Android 系统中一个非常重要的进程。在 Android 系统中，应用程序出现问题，对系统影响不大，而 Init、Zygote、SystemServer 三大进程对系统的影响则非常大，因为其中任何一个 crash，都会造成系统崩溃，出现重启现象。
zygote fork SystemServer 进程
SystemServer 是由 Zygote 孵化而来的一个进程，通过 ps 命令，我们发现其进程名为：system_server。在分析 zygote 进程时，我们知道当 zygote 进程进入到 java 世界后，在 ZygoteInit.java 中，将调用 forkSystemServer 方法启动 SystemServer 进程。
// frameworks/base/core/java/com/android/internal/os/ZygoteInit.java
public class ZygoteInit {
public static void main(String argv[]) {
try {
if (startSystemServer) {
// fork 出 system_server
Runnable r = forkSystemServer(abiList, zygoteSocketName, zygoteServer);
if (r != null) {
r.run();
return;
}
}
}
}
private static Runnable forkSystemServer(String abiList, String socketName,
ZygoteServer zygoteServer) {
try {
... ...
/* Request to fork the system server process */
pid = Zygote.forkSystemServer(
parsedArgs.mUid, parsedArgs.mGid,
parsedArgs.mGids,
parsedArgs.mRuntimeFlags,
null,
parsedArgs.mPermittedCapabilities,
parsedArgs.mEffectiveCapabilities);
} catch (IllegalArgumentException ex) {
throw new RuntimeException(ex);
}
}
}......
SystemServer启动流程
1、SystemServer.main()
接下来就进到了 SystemServer.java 的 main() 函数处理流程：
// frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer {
/**
* The main entry point from zygote.
*/
public static void main(String[] args) {
new SystemServer().run(); // 创建并运行，简单粗暴！
}
}这里直接 new 出一个 SystemServer 对象 并执行其 run() 方法。
2、SystemServer.run()
// frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer {
private void run() {
try {
traceBeginAndSlog("InitBeforeStartServices");
... ...
// 如果系统时钟早于1970年，则设置系统始终从1970年开始
if (System.currentTimeMillis() < EARLIEST_SUPPORTED_TIME) {
Slog.w(TAG, "System clock is before 1970; setting to 1970.");
SystemClock.setCurrentTimeMillis(EARLIEST_SUPPORTED_TIME);
}
... ...
if (!SystemProperties.get("persist.sys.language").isEmpty()) {
// 设置区域，语言等选项
final String languageTag = Locale.getDefault().toLanguageTag();
SystemProperties.set("persist.sys.locale", languageTag);
SystemProperties.set("persist.sys.language", "");
SystemProperties.set("persist.sys.country", "");
SystemProperties.set("persist.sys.localevar", "");
}
... ...
// 清除 vm 内存增长上限，由于启动过程需要较多的虚拟机内存空间
VMRuntime.getRuntime().clearGrowthLimit();
// 设置堆栈利用率，GC 后会重新计算堆栈空间大小
VMRuntime.getRuntime().setTargetHeapUtilization(0.8f);
// 针对部分设备依赖于运行时就产生指纹信息，因此需要在开机完成前已经定义
Build.ensureFingerprintProperty();
// 访问环境变量前，需要明确地指定用户
Environment.setUserRequired(true);
... ...
// 加载动态库 libandroid_services.so
System.loadLibrary("android_servers");
// 检测上次关机过程是否失败，该方法可能不会返回
performPendingShutdown();
// 在 SystemServer 进程中也需要创建 Context 对象，初始化系统上下文
createSystemContext();
// 创建 SystemServiceManager 对象
mSystemServiceManager = new SystemServiceManager(mSystemContext);
// SystemServer 进程主要是用来构建系统各种 service 服务，
// 而 SystemServiceManager 就是这些服务的管理对象
mSystemServiceManager.setStartInfo(mRuntimeRestart,
mRuntimeStartElapsedTime, mRuntimeStartUptime);
// 将 SystemServiceManager 对象保存到 SystemServer 进程中的一个数据结构中
LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
// Prepare the thread pool for init tasks that can be parallelized
SystemServerInitThreadPool.get();
} finally {
traceEnd(); // InitBeforeStartServices
}
// Start services.
try {
traceBeginAndSlog("StartServices");
startBootstrapServices(); // 主要用于启动系统 Boot 级服务
startCoreServices(); // 主要用于启动系统核心的服务
startOtherServices(); // 主要用于启动一些非紧要或者非需要及时启动的服务
} catch (Throwable ex) {
Slog.e("System", "******************************************");
Slog.e("System", "************ Failure starting system services", ex);
throw ex;
} finally {
traceEnd();
}
... ...
// 启动looper，以处理到来的消息，一直循环执行
Looper.loop();
throw new RuntimeException("Main thread loop unexpectedly exited");
}
}以上就是 SystemServer.run() 方法的整个流程，简化如下
// frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer {
private void run() {
try {
// Initialize the system context.
createSystemContext(); // 01. 初始化系统上下文
// 02. 创建系统服务管理
mSystemServiceManager = new SystemServiceManager(mSystemContext);
mSystemServiceManager.setRuntimeRestarted(mRuntimeRestart);
LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
} finally {
traceEnd(); // InitBeforeStartServices
}
// 03.启动系统各种服务
try {
startBootstrapServices(); // 启动引导服务
startCoreServices(); // 启动核心服务
startOtherServices(); // 启动其他服务
}
// Loop forever.
Looper.loop(); // 一直循环执行
throw new RuntimeException("Main thread loop unexpectedly exited");
}
}接下来我们针对 SystemServer 所做的 三部分工作 单独分析！
3、初始化系统上下文
// frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer {
private void createSystemContext() {
ActivityThread activityThread = ActivityThread.systemMain();
mSystemContext = activityThread.getSystemContext();
mSystemContext.setTheme(DEFAULT_SYSTEM_THEME);
final Context systemUiContext = activityThread.getSystemUiContext();
systemUiContext.setTheme(DEFAULT_SYSTEM_THEME);
}
}跟踪 systemMain() 方法
// frameworks/base/core/java/android/app/ActivityThread.java
public final class ActivityThread extends ClientTransactionHandler {
public static ActivityThread systemMain() {
// The system process on low-memory devices do not get to use hardware
// accelerated drawing, since this can add too much overhead to the
// process.
if (!ActivityManager.isHighEndGfx()) {
ThreadedRenderer.disable(true); // 对于低内存的设备，禁用硬件加速
} else {
ThreadedRenderer.enableForegroundTrimming();
}
ActivityThread thread = new ActivityThread();
thread.attach(true, 0); // 调用 attach() 方法
return thread;
}
}跟踪 attach() 方法
// frameworks/base/core/java/android/app/ActivityThread.java
public final class ActivityThread extends ClientTransactionHandler {
private void attach(boolean system, long startSeq) {
sCurrentActivityThread = this;
mSystemThread = system;
if (!system) {
... ...
} else {
// Don't set application object here -- if the system crashes,
// we can't display an alert, we just want to die die die.
// 设置 SystemServer 进程在 DDMS 中显示的名字为 "system_process"
android.ddm.DdmHandleAppName.setAppName("system_process",
UserHandle.myUserId()); // 如不设置，则显示"?"，无法调试该进程
try {
mInstrumentation = new Instrumentation();
mInstrumentation.basicInit(this);
// 首先通过 getSystemContext() 创建系统上下文，然后创建应用上下文
ContextImpl context = ContextImpl.createAppContext(
this, getSystemContext().mPackageInfo);
// 创建 Application
mInitialApplication = context.mPackageInfo.makeApplication(true, null);
// 调用 Application的 onCreate()
mInitialApplication.onCreate();
} catch (Exception e) {
throw new RuntimeException(
"Unable to instantiate Application():" + e.toString(), e);
}
}
... ...
ViewRootImpl.ConfigChangedCallback configChangedCallback
= (Configuration globalConfig) -> {
synchronized (mResourcesManager) {
// We need to apply this change to the resources immediately, because upon returning
// the view hierarchy will be informed about it.
if (mResourcesManager.applyConfigurationToResourcesLocked(globalConfig,
null /* compat */)) {
updateLocaleListFromAppContext(mInitialApplication.getApplicationContext(),
mResourcesManager.getConfiguration().getLocales());
// This actually changed the resources! Tell everyone about it.
if (mPendingConfiguration == null
|| mPendingConfiguration.isOtherSeqNewer(globalConfig)) {
mPendingConfiguration = globalConfig;
sendMessage(H.CONFIGURATION_CHANGED, globalConfig);
}
}
}
};
// 添加回调
ViewRootImpl.addConfigCallback(configChangedCallback);
}
}我们发现 attach() 方法主要做了四件事：
（1）创建系统上下文：getSystemContext()；
（2）创建应用上下文：createAppContext()；
（3）创建 Application：makeApplication()；
（4）添加回调 configChangedCallback 到 ViewRootImpl。
（1）创建系统上下文
// frameworks/base/core/java/android/app/ActivityThread.java
public final class ActivityThread extends ClientTransactionHandler {
public ContextImpl getSystemContext() {
synchronized (this) {
if (mSystemContext == null) {
mSystemContext = ContextImpl.createSystemContext(this);
}
return mSystemContext;
}
}
}// frameworks/base/core/java/android/app/ContextImpl.java
class ContextImpl extends Context {
static ContextImpl createSystemContext(ActivityThread mainThread) {
// 这边 new 出来的 LoadedApk 将作为创建应用上下文的参数 packageInfo
LoadedApk packageInfo = new LoadedApk(mainThread);
// ContextImpl() 创建系统上下文
ContextImpl context = new ContextImpl(null, mainThread, packageInfo, null, null, null, 0,
null, null);
context.setResources(packageInfo.getResources());
context.mResources.updateConfiguration(context.mResourcesManager.getConfiguration(),
context.mResourcesManager.getDisplayMetrics());
return context;
}
}（2）创建应用上下文
// frameworks/base/core/java/android/app/ContextImpl.java
class ContextImpl extends Context {
static ContextImpl createAppContext(ActivityThread mainThread, LoadedApk packageInfo) {
return createAppContext(mainThread, packageInfo, null);
}
static ContextImpl createAppContext(ActivityThread mainThread, LoadedApk packageInfo,
String opPackageName) {
if (packageInfo == null) throw new IllegalArgumentException("packageInfo");
// ContextImpl()创建应用上下文
ContextImpl context = new ContextImpl(null, mainThread, packageInfo, null, null, null, 0,
null, opPackageName);
context.setResources(packageInfo.getResources());
return context;
}
}我们可以看出：new ContextImpl() 时，系统上下文和应用上下文的参数是一样的，createAppContext() 中的参数 packageInfo，就是 createSystemContext() 中 new 的 LoadedApk。
创建完成之后，系统上下文赋值给了 ActivityThread 的成员变量 mSystemContext，而应用上下文只是作为函数中的局部变量临时使用。
（3）创建 Application
// frameworks/base/core/java/android/app/LoadedApk.java
public final class LoadedApk {
public Application makeApplication(boolean forceDefaultAppClass,
Instrumentation instrumentation) {
if (mApplication != null) {
return mApplication;
}
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "makeApplication");
Application app = null;
String appClass = mApplicationInfo.className;
if (forceDefaultAppClass || (appClass == null)) { // forceDefaultAppClass 为 true
appClass = "android.app.Application";
}
try {
java.lang.ClassLoader cl = getClassLoader();
// 此 LoadedApk 对象是 createSystemContext 时 new 的，mPackageName = "android"
if (!mPackageName.equals("android")) {
initializeJavaContextClassLoader();
}
// 又创建了一个局部应用上下文
ContextImpl appContext = ContextImpl.createAppContext(mActivityThread, this);
// 创建 Application
app = mActivityThread.mInstrumentation.newApplication(
cl, appClass, appContext);
appContext.setOuterContext(app);
} catch (Exception e) {
if (!mActivityThread.mInstrumentation.onException(app, e)) {
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
throw new RuntimeException(
"Unable to instantiate application " + appClass
+ ": " + e.toString(), e);
}
}
// 将前面创建的 app 添加到应用列表
mActivityThread.mAllApplications.add(app);
mApplication = app;
... ...
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
return app;
}
}4、创建系统服务管理
回顾下创建系统服务管理相关代码：
// frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer {
private void run() {
try {
// Initialize the system context.
createSystemContext(); // 01. 初始化系统上下文
// 02. 创建系统服务管理
mSystemServiceManager = new SystemServiceManager(mSystemContext);
mSystemServiceManager.setRuntimeRestarted(mRuntimeRestart);
LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
} finally {
traceEnd(); // InitBeforeStartServices
}
... ...
}这一步只是 new 了一个 SystemServiceManager，并将其添加到本地服务列表中。mSystemContext 为第一步中创建的系统上下文。本地服务列表是以类为 key 保存的一个列表，即列表中某种类型的对象最多只能有一个。
new SystemServiceManager()
// frameworks/base/services/core/java/com/android/server/SystemServiceManager.java
public class SystemServiceManager {
... ...
// 系统服务列表，系统服务必须继承 SystemService
private final ArrayList<SystemService> mServices = new ArrayList<SystemService>();
// 当前处于开机过程的哪个阶段
private int mCurrentPhase = -1;
SystemServiceManager(Context context) {
mContext = context;
}
@SuppressWarnings("unchecked")
// 通过类名启动系统服务，可能会找不到类而抛异常
public SystemService startService(String className) {
final Class<SystemService> serviceClass;
try {
serviceClass = (Class<SystemService>)Class.forName(className);
} catch (ClassNotFoundException ex) {
Slog.i(TAG, "Starting " + className);
throw new RuntimeException("Failed to create service " + className
+ ": service class not found, usually indicates that the caller should "
+ "have called PackageManager.hasSystemFeature() to check whether the "
+ "feature is available on this device before trying to start the "
+ "services that implement it", ex);
}
return startService(serviceClass);
}
@SuppressWarnings("unchecked")
// 创建并启动系统服务，系统服务类必须继承 SystemService
public <T extends SystemService> T startService(Class<T> serviceClass) {
try {
final String name = serviceClass.getName();
Slog.i(TAG, "Starting " + name);
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "StartService " + name);
// Create the service.
if (!SystemService.class.isAssignableFrom(serviceClass)) {
throw new RuntimeException("Failed to create " + name
+ ": service must extend " + SystemService.class.getName());
}
final T service;
try {
Constructor<T> constructor = serviceClass.getConstructor(Context.class);
service = constructor.newInstance(mContext);
} catch (InstantiationException ex) {
... ...
}
startService(service);
return service;
} finally {
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
}
}
public void startService(@NonNull final SystemService service) {
// Register it.
mServices.add(service);
// Start it.
long time = SystemClock.elapsedRealtime();
try {
service.onStart();
} catch (RuntimeException ex) {
throw new RuntimeException("Failed to start service " + service.getClass().getName()
+ ": onStart threw an exception", ex);
}
warnIfTooLong(SystemClock.elapsedRealtime() - time, service, "onStart");
}
// 通知系统服务到了开机的哪个阶段，会遍历调用所有系统服务的 onBootPhase() 函数
public void startBootPhase(final int phase) {
... ...
try {
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "OnBootPhase " + phase);
final int serviceLen = mServices.size();
for (int i = 0; i < serviceLen; i++) {
final SystemService service = mServices.get(i);
long time = SystemClock.elapsedRealtime();
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, service.getClass().getName());
try {
service.onBootPhase(mCurrentPhase);
} catch (Exception ex) {
throw new RuntimeException("Failed to boot service "
+ service.getClass().getName()
+ ": onBootPhase threw an exception during phase "
+ mCurrentPhase, ex);
}
warnIfTooLong(SystemClock.elapsedRealtime() - time, service, "onBootPhase");
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
}
} finally {
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
}
}
}5、启动系统各种服务
// frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer {
private void run() {
// 01. 初始化系统上下文
// 02. 创建系统服务管理
// 03.启动系统各种服务
try {
startBootstrapServices(); // 启动引导服务
startCoreServices(); // 启动核心服务
startOtherServices(); // 启动其他服务
}
// Loop forever.
Looper.loop(); // 一直循环执行
throw new RuntimeException("Main thread loop unexpectedly exited");
}
}（1）启动引导服务startBootstrapServices()
// frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer {
/**
* Starts the small tangle of critical services that are needed to get the system off the
* ground. These services have complex mutual dependencies which is why we initialize them all
* in one place here. Unless your service is also entwined in these dependencies, it should be
* initialized in one of the other functions.
*/
private void startBootstrapServices() {
... ...
// 启动 Installer 服务，阻塞等待与 installd 建立 socket 通道
Installer installer = mSystemServiceManager.startService(Installer.class);
mSystemServiceManager.startService(DeviceIdentifiersPolicyService.class);
mSystemServiceManager.startService(UriGrantsManagerService.Lifecycle.class);
// 启动 ActivityManagerService
ActivityTaskManagerService atm = mSystemServiceManager.startService(
ActivityTaskManagerService.Lifecycle.class).getService();
mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
mActivityManagerService.setInstaller(installer);
mWindowManagerGlobalLock = atm.getGlobalLock();
// 启动 PowerManagerService
mPowerManagerService = mSystemServiceManager.startService(PowerManagerService.class);
mSystemServiceManager.startService(ThermalManagerService.class);
// PowerManagerService 就绪，AMS 初始化电源管理
mActivityManagerService.initPowerManagement();
mActivityManagerService.initPowerManagement();
mSystemServiceManager.startService(RecoverySystemService.class);
RescueParty.noteBoot(mSystemContext);
// 启动 LightsService
mSystemServiceManager.startService(LightsService.class);
// 启动 DisplayManagerService
mDisplayManagerService = mSystemServiceManager.startService(DisplayManagerService.class);
// We need the default display before we can initialize the package manager.
mSystemServiceManager.startBootPhase(SystemService.PHASE_WAIT_FOR_DEFAULT_DISPLAY);
// 当设备正在加密时，仅运行核心应用
String cryptState = SystemProperties.get("vold.decrypt");
if (ENCRYPTING_STATE.equals(cryptState)) {
Slog.w(TAG, "Detected encryption in progress - only parsing core apps");
mOnlyCore = true;
} else if (ENCRYPTED_STATE.equals(cryptState)) {
Slog.w(TAG, "Device encrypted - only parsing core apps");
mOnlyCore = true;
}
// Start the package manager.
if (!mRuntimeRestart) {
MetricsLogger.histogram(null, "boot_package_manager_init_start",
(int) SystemClock.elapsedRealtime());
}
// 启动 PackageManagerService
try {
Watchdog.getInstance().pauseWatchingCurrentThread("packagemanagermain");
mPackageManagerService = PackageManagerService.main(mSystemContext, installer,
mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF, mOnlyCore);
} finally {
Watchdog.getInstance().resumeWatchingCurrentThread("packagemanagermain");
}
mFirstBoot = mPackageManagerService.isFirstBoot();
mPackageManager = mSystemContext.getPackageManager();
... ...
// 将 UserManagerService 添加到服务列表，该服务是在 PackageManagerService 中初始化的
mSystemServiceManager.startService(UserManagerService.LifeCycle.class);
// 初始化用来缓存包资源的属性缓存
AttributeCache.init(mSystemContext);
// Set up the Application instance for the system process and get started.
mActivityManagerService.setSystemProcess();
... ...
mSensorServiceStart = SystemServerInitThreadPool.get().submit(() -> {
TimingsTraceLog traceLog = new TimingsTraceLog(
SYSTEM_SERVER_TIMING_ASYNC_TAG, Trace.TRACE_TAG_SYSTEM_SERVER);
traceLog.traceBegin(START_SENSOR_SERVICE);
startSensorService(); // 启动传感器服务
traceLog.traceEnd();
}, START_SENSOR_SERVICE);
}
}首先等待 installd 启动完成，然后启动一些相互依赖的关键服务。
（2）启动核心服务startCoreServices()
// frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer {
/**
* Starts some essential services that are not tangled up in the bootstrap process.
*/
private void startCoreServices() {
// 启动 BatteryService，用于统计电池电量，需要 LightService
mSystemServiceManager.startService(BatteryService.class);
// 启动 UsageStatsService，用于统计应用使用情况
mSystemServiceManager.startService(UsageStatsService.class);
mActivityManagerService.setUsageStatsManager(
LocalServices.getService(UsageStatsManagerInternal.class));
// 启动 WebViewUpdateService
if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_WEBVIEW)) {
mWebViewUpdateService = mSystemServiceManager.startService(WebViewUpdateService.class);
}
.... ...
}
}（3）启动其他服务startOtherServices()
代码很长（1200多行...），但是逻辑简单，主要是启动各种服务。
// frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer {
/**
* Starts a miscellaneous grab bag of stuff that has yet to be refactored and organized.
*/
private void startOtherServices() {
... ...
try {
... ...
// 调度策略
ServiceManager.addService("scheduling_policy", new SchedulingPolicyService());
mSystemServiceManager.startService(TelecomLoaderService.class);
// 提供电话注册、管理服务，可以获取电话的链接状态、信号强度等
telephonyRegistry = new TelephonyRegistry(context);
ServiceManager.addService("telephony.registry", telephonyRegistry);
mEntropyMixer = new EntropyMixer(context);
mContentResolver = context.getContentResolver();
// 提供所有账号、密码、认证管理等等的服务
mSystemServiceManager.startService(ACCOUNT_SERVICE_CLASS);
... ...
// 振动器服务
vibrator = new VibratorService(context);
ServiceManager.addService("vibrator", vibrator);
... ...
inputManager = new InputManagerService(context);
// WMS needs sensor service ready
ConcurrentUtils.waitForFutureNoInterrupt(mSensorServiceStart, START_SENSOR_SERVICE);
mSensorServiceStart = null;
wm = WindowManagerService.main(context, inputManager, !mFirstBoot, mOnlyCore,
new PhoneWindowManager(), mActivityManagerService.mActivityTaskManager);
ServiceManager.addService(Context.WINDOW_SERVICE, wm, /* allowIsolated= */ false,
DUMP_FLAG_PRIORITY_CRITICAL | DUMP_FLAG_PROTO);
ServiceManager.addService(Context.INPUT_SERVICE, inputManager,
/* allowIsolated= */ false, DUMP_FLAG_PRIORITY_CRITICAL);
... ...
} catch (RuntimeException e) {
Slog.e("System", "******************************************");
Slog.e("System", "************ Failure starting core service", e);
}
... ...
LockSettingsService // 屏幕锁定服务，管理每个用户的相关锁屏信息
DeviceIdleController // Doze模式的主要驱动
DevicePolicyManagerService // 提供一些系统级别的设置及属性
StatusBarManagerService // 状态栏管理服务
ClipboardService // 系统剪切板服务
NetworkManagementService // 网络管理服务
TextServicesManagerService // 文本服务，例如文本检查等
NetworkScoreService // 网络评分服务
NetworkStatsService // 网络状态服务
NetworkPolicyManagerService // 网络策略服务
WifiP2pService // Wifi Direct服务
WifiService // Wifi服务
WifiScanningService // Wifi扫描服务
RttService // Wifi相关
EthernetService // 以太网服务
ConnectivityService // 网络连接管理服务
NsdService // 网络发现服务
NotificationManagerService // 通知栏管理服务
DeviceStorageMonitorService // 磁盘空间状态检测服务
LocationManagerService // 位置服务，GPS、定位等
CountryDetectorService // 检测用户国家
SearchManagerService // 搜索管理服务
DropBoxManagerService // 用于系统运行时日志的存储于管理
WallpaperManagerService // 壁纸管理服务
AudioService // AudioFlinger的上层管理封装，主要是音量、音效、声道及铃声等的管理
DockObserver // 如果系统有个座子，当手机装上或拔出这个座子的话，就得靠他来管理了
WiredAccessoryManager // 监视手机和底座上的耳机
UsbService // USB服务
SerialService // 串口服务
TwilightService // 指出用户当前所在位置是否为晚上，被 UiModeManager 等用来调整夜间模式
BackupManagerService // 备份服务
AppWidgetService // 提供Widget的管理和相关服务
VoiceInteractionManagerService // 语音交互管理服务
DiskStatsService // 磁盘统计服务，供dumpsys使用
SamplingProfilerService // 用于耗时统计等
NetworkTimeUpdateService // 监视网络时间，当网络时间变化时更新本地时间。
CertBlacklister // 提供一种机制更新SSL certificate blacklist
DreamManagerService // 屏幕保护
PrintManagerService // 打印服务
HdmiControlService // HDMI控制服务
FingerprintService // 指纹服务
... ...
}
}总结
可以看到PowerManagerService先于AudioService启动，此时如果在PowerManagerService启动后立刻调用AudioService中的接口就会引发 JE 崩溃，进而导致system_server崩溃。
![[手机Linux] 七，NextCloud优化设置](https://i-blog.csdnimg.cn/direct/958bff6eb035463d9b2bd3d30edbb65d.png)
