Android(安卓)process

In this topic you will learn some information about Android process management. First let’s take a look at the launched processes during Android booting.

USER PID PPID VSIZE RSS WCHAN PC NAME

root 1 0 264 176 c00acc6c 0000c36c S /init
root 28 1 724 308 c0051354 afe0c4cc S /system/bin/sh
system 30 1 796 248 c026516c afe0b74c S /system/bin/servicemanager
root 31 1 1824 316 ffffffff afe0b50c S /system/bin/mountd
root 32 1 652 248 c02976e0 afe0c0bc S /system/bin/debuggerd
radio 33 1 5344 664 ffffffff afe0bdbc S /system/bin/rild
root 34 1 71028 18828 c00ad308 afe0b874 S zygote
media 37 1 16812 3456 ffffffff afe0b74c S /system/bin/mediaserver
root 39 1 788 288 c02f9ae4 afe0b50c S /system/bin/installd
system 86 34 187756 21836 ffffffff afe0b74c S system_server
radio 118 34 103476 13896 ffffffff afe0c824 S com.android.phone
app_4 124 34 117848 19248 ffffffff afe0c824 S android.process.acore
app_5 139 34 98672 11516 ffffffff afe0c824 S com.android.mms
app_3 151 34 92096 10976 ffffffff afe0c824 S com.android.alarmclock
app_6 161 34 94436 12616 ffffffff afe0c824 S com.android.calendar
app_9 173 34 93248 11728 ffffffff afe0c824 S android.process.media
app_15 182 34 91848 9764 ffffffff afe0c824 S com.android.voicedialer
app_16 190 34 94524 10812 ffffffff afe0c824 S android.process.im

They can be divided into three kinds.

(1)Root Process
init is the first process after kernel booting. The major task it performs:

--Parser and execute init.rc and init.%hardware%.rc
--Automatically generate device node under /dev
--Start log and property service
--Monitor for device, property set and child process exit events

(2)Native Application Process
According to init.rc, init will fork the following native application process.

console: star a shell.
servicemanager : start binder IPC service manager.
mountd : mount all fs defined in /system/etc/mountd.conf if started, receive commands through local socket to mount any fs.
debuggerd : start debug system.
rild : start radio interface layer daemon.
zygote : start Android Java VM Runtime and start system server. It’s the most important process.
mediaserver : start AudioFlinger, MediaPlayerService and CameraService.
installd : start install package daemon.

(3)JAVA Application Process
Every JAVA application process is forked from zygote process. system_server is a special JAVA process, which is directly forked from zygote.. Other JAVA process is created from ActivityManagerService(run in system_server process) like this.

int pid = Process.start("android.app.ActivityThread",
mSimpleProcessManagement ? app.processName : null, uid, uid,
gids, ((app.info.flags&ApplicationInfo.FLAG_DEBUGGABLE) != 0), null);

-->System Server
It’s the first JAVA application launched by zygote. It starts the core Android services, e.g. ActivityManager, WindowManager, PackageManager etc. It’s the Android core engine.

-->Persistent Application
During booting, ActivityManagerService.systemReady will start all persistent applications.

List apps = ActivityThread.getPackageManager().getPersistentApplications(PackageManager.GET_SHARED_LIBRARY_FILES);

if (apps != null) {
int N = apps.size();
int i;
for (i=0; i<N; i++) {
ApplicationInfo info = (ApplicationInfo)apps.get(i);
if (info != null &&!info.packageName.equals("android")) {
addAppLocked(info);
}}}

Currently only Phone application is registered as a persistent appin AndroidManifest.xml like this.

So during booting, only phone application is automatically launched. It’s the “com.android.phone” process.

-->The First Activity
The first activity is launched by senting Intent.CATEGORY_HOME intent from ActivityManagerService.

Intent intent = new Intent(mTopAction,mTopData != null ? Uri.parse(mTopData) : null);
intent.setComponent(mTopComponent);

if (mFactoryTest != SystemServer.FACTORY_TEST_LOW_LEVEL) {
intent.addCategory(Intent.CATEGORY_HOME );}

ActivityInfo aInfo = intent.resolveActivityInfo(mContext.getPackageManager(),PackageManager.GET_SHARED_LIBRARY_FILES);

if (aInfo != null) {
intent.setComponent(new ComponentName(
aInfo.applicationInfo.packageName, aInfo.name));
// Don't do this if the home app is currently being instrumented.
ProcessRecord app = getProcessRecordLocked(aInfo.processName, aInfo.applicationInfo.uid);

if (app == null || app.instrumentationClass == null) {
intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK);
startActivityLocked(null, intent, null, null, 0, aInfo, null, null, 0, 0, 0, false);
}}

It’s the “android.process.acore” process. (The process name is defined in AndroidManifest.xml)

-->Auto-launched Application After Booting
When activity idle is detected in ActivityManagerService, it will broadcast ACTION_BOOT_COMPLETED intent at the first time.

if (mFactoryTest != SystemServer.FACTORY_TEST_LOW_LEVEL) {
// Tell anyone interested that we are done booting!
synchronized (this) {
broadcastIntentLocked(null, null, new Intent(Intent.ACTION_BOOT_COMPLETED , null),
null, null, 0, null, null,android.Manifest.permission.RECEIVE_BOOT_COMPLETED,
false, false, MY_PID, Process.SYSTEM_UID);}}

Currently, MMS, AlarmClock, Calendar, MediaProvider, VoiceDialer and IM have registered as a receiver for ACTION_BOOT_COMPLETED intent in their AndroidManifest.xml. So they will be automatically launched. (This explains the remained JAVA process.)

Email also registers as a receiver for ACTION_BOOT_COMPLETED intent in its AndroidManifest.xml, but it defines android:enable=”false”. So it won’t be launched.

DownloadProvider also registers as a receiver for ACTION_BOOT_COMPLETED intent in its AndroidManifest.xml, but it defines android:exported=”false”. So it won’t be launched.

转自：http://blog.csdn.net/mawl2002/archive/2009/06/25/4295905.aspx

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