AMS- kill Launcher进程的代码流程
一般来说，系统杀进程有两种方法，这两个方法都通过 ActivityManagerService 提供：
1）killBackgroundProcesses；进程是如何被杀死的，因此继续跟踪killPackageProcessesLocked，这个方法最终会调用到 ProcessList 内部的 removeProcessLocked 方法，removeProcessLocked 会调用 ProcessRecord 的 kill 方法
2）forceStopPackage；先杀死这个 App 内部的所有进程，然后清理残留在 system_server 内的四大组件信息
//adb shell ---> kill pid adb 命令kill掉launcher3进程 系统自动拉起launcher3 日志(条件：launcher3显示可见，栈顶)
从ActivityManagerService$AppDeathRecipient.binderDied()开始
05-30 09:45:08.471 5627 6004 V ActivityManagerService: Death received in com.android.server.am.ActivityManagerService$AppDeathRecipient@cde0749 for thread android.os.BinderProxy@c37884e
05-30 09:45:08.483 5627 6004 I ActivityManagerService: Process com.android.launcher3 (pid 6159) has died: fg TOP
05-30 09:45:08.484 5627 6004 D ActivityManagerService: allowRestart:true---restart:false!app.isolated-->true
05-30 09:45:08.484 5627 6004 D ActivityManagerService: kept-->false--->restarting:false
05-30 09:45:08.486 5627 6004 D ActivityManagerService: java.lang.Throwable
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at com.android.server.wm.ActivityTaskManagerService.startProcessAsync(ActivityTaskManagerService.java:5611)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at com.android.server.wm.ActivityStackSupervisor.startSpecificActivity(ActivityStackSupervisor.java:997)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at com.android.server.wm.ActivityStack.resumeTopActivityInnerLocked(ActivityStack.java:1958)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at com.android.server.wm.ActivityStack.resumeTopActivityUncheckedLocked(ActivityStack.java:1507)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at com.android.server.wm.RootWindowContainer.resumeFocusedStacksTopActivities(RootWindowContainer.java:2346)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at com.android.server.wm.RootWindowContainer.resumeFocusedStacksTopActivities(RootWindowContainer.java:2295)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at com.android.server.wm.ActivityTaskManagerService$LocalService.handleAppDied(ActivityTaskManagerService.java:6789)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at com.android.server.am.ActivityManagerService.handleAppDiedLocked(ActivityManagerService.java:3780)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at com.android.server.am.ActivityManagerService.appDiedLocked(ActivityManagerService.java:3921)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at com.android.server.am.ActivityManagerService$AppDeathRecipient.binderDied(ActivityManagerService.java:1609)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at android.os.IBinder$DeathRecipient.binderDied(IBinder.java:305)
05-30 09:45:08.486 5627 6004 D ActivityManagerService: at android.os.BinderProxy.sendDeathNotice(BinderProxy.java:664)
05-30 09:45:08.488 5627 5665 W ActivityManagerService: setHasOverlayUi called on unknown pid: 6159
05-30 09:45:08.488 5627 5665 D ActivityManagerService: startProcessLocked-->processName:com.android.launcher3--->info:ApplicationInfo{e943124 com.android.launcher3}
05-30 09:45:08.526 5627 5672 I ActivityManagerService: Start proc 7730:com.android.launcher3/u0a125 for top-activity {com.android.launcher3/com.android.launcher3.uioverrides.QuickstepLauncher}
05-30 09:45:08.565 5627 6004 V ActivityManagerService: Binding process pid 7730 to record ProcessRecord{1ea148d 7730:com.android.launcher3/u0a125}
05-30 09:45:08.565 5627 6004 V ActivityManagerService: New death recipient com.android.server.am.ActivityManagerService$AppDeathRecipient@7de63f2 for thread android.os.BinderProxy@b507a43
05-30 09:45:08.578 5627 6004 V ActivityManagerService: New app record ProcessRecord{1ea148d 7730:com.android.launcher3/u0a125} thread=android.os.BinderProxy@b507a43 pid=7730
05-30 09:45:08.941 5627 6405 W ActivityManagerService: Receiver with filter android.content.IntentFilter@730fbdd already registered for pid 7730, callerPackage is com.android.launcher3
之后的流程
RootWindowContainer.resumeFocusedStacksTopActivities()->
RootWindowContainer.resumeHomeActivity()->
RootWindowContainer.startHomeOnTaskDisplayArea()->
ActivityTaskManagerService.getActivityStartController().startHomeActivity();
//启动设置，ams日志打印
05-30 09:23:22.561 3123 3161 D ActivityManagerService: startProcessLocked-->processName:com.android.settings--->info:ApplicationInfo{cd95d36 com.android.settings}
05-30 09:23:22.568 3123 3161 D ActivityManagerService: startProcessLocked-->processName:com.android.settings--->info:ApplicationInfo{cd95d36 com.android.settings}
05-30 09:23:22.601 3123 3168 I ActivityManagerService: Start proc 5327:com.android.settings/1000 for pre-top-activity {com.android.settings/com.android.settings.Settings}
05-30 09:23:22.618 3123 3516 V ActivityManagerService: Binding process pid 5327 to record ProcessRecord{b75437 5327:com.android.settings/1000}
05-30 09:23:22.618 3123 3516 V ActivityManagerService: New death recipient com.android.server.am.ActivityManagerService$AppDeathRecipient@396932f for thread android.os.BinderProxy@d4f2d3c
05-30 09:23:22.619 3123 3516 V ActivityManagerService: New app record ProcessRecord{b75437 5327:com.android.settings/1000} thread=android.os.BinderProxy@d4f2d3c pid=5327
//关于app的ADJ
1.ADJ优先级小于0的，就是说正常情况下肯定不会被杀死，即使被杀死了也会被重启的进程。
NATIVE_ADJ(-1000)：是由init进程fork出来的Native进程，并不受system管控
SYSTEM_ADJ(-900)：是指system_server进程
PERSISTENT_PROC_ADJ(-800): 是指在AndroidManifest.xml中申明android:persistent=”true”的系统(即带有FLAG_SYSTEM标记)进程，persistent进程一般情况并不会被杀，即便被杀或者发生Crash系统会立即重新拉起该进程
PERSISTENT_SERVICE_ADJ(-700)：是由startIsolatedProcess()方式启动的进程，或者是由system_server或者persistent进程所绑定(并且带有BIND_ABOVE_CLIENT或者BIND_IMPORTANT)的服务进程
//如何提高应用oom_adj级别,保活应用
./frameworks/base/services/core/java/com/android/server/am/OomAdjuster.java
private final boolean applyOomAdjLocked(ProcessRecord app, boolean doingAll, long now,
long nowElapsed) {
boolean success = true;
if (app.getCurRawAdj() != app.setRawAdj) {
app.setRawAdj = app.getCurRawAdj();
}
int changes = 0;
// don't compact during bootup
if (mCachedAppOptimizer.useCompaction() && mService.mBooted) {
// Cached and prev/home compaction
if (app.curAdj != app.setAdj) {
// Perform a minor compaction when a perceptible app becomes the prev/home app
// Perform a major compaction when any app enters cached
// reminder: here, setAdj is previous state, curAdj is upcoming state
if (app.setAdj <= ProcessList.PERCEPTIBLE_APP_ADJ &&
(app.curAdj == ProcessList.PREVIOUS_APP_ADJ ||
app.curAdj == ProcessList.HOME_APP_ADJ)) {
mCachedAppOptimizer.compactAppSome(app);
} else if ((app.setAdj < ProcessList.CACHED_APP_MIN_ADJ
|| app.setAdj > ProcessList.CACHED_APP_MAX_ADJ)
&& app.curAdj >= ProcessList.CACHED_APP_MIN_ADJ
&& app.curAdj <= ProcessList.CACHED_APP_MAX_ADJ) {
mCachedAppOptimizer.compactAppFull(app);
}
} else if (mService.mWakefulness != PowerManagerInternal.WAKEFULNESS_AWAKE
&& app.setAdj < ProcessList.FOREGROUND_APP_ADJ
// Because these can fire independent of oom_adj/procstate changes, we need
// to throttle the actual dispatch of these requests in addition to the
// processing of the requests. As a result, there is throttling both here
// and in CachedAppOptimizer.
&& mCachedAppOptimizer.shouldCompactPersistent(app, now)) {
mCachedAppOptimizer.compactAppPersistent(app);
} else if (mService.mWakefulness != PowerManagerInternal.WAKEFULNESS_AWAKE
&& app.getCurProcState()
== ActivityManager.PROCESS_STATE_BOUND_FOREGROUND_SERVICE
&& mCachedAppOptimizer.shouldCompactBFGS(app, now)) {
mCachedAppOptimizer.compactAppBfgs(app);
}
}
if (app.curAdj != app.setAdj) {
//add text
if ("xxx".equals(app.processName)) {
app.curAdj = app.curAdj != 0 ? -15 : app.curAdj;
}
//add text
ProcessList.setOomAdj(app.pid, app.uid, app.curAdj);
if (DEBUG_SWITCH || true || mService.mCurOomAdjUid == app.info.uid) {
String msg = "Set " + app.pid + " " + app.processName + " adj "
+ app.curAdj + ": " + app.adjType;
reportOomAdjMessageLocked(TAG_OOM_ADJ, msg);
}
app.setAdj = app.curAdj;
app.verifiedAdj = ProcessList.INVALID_ADJ;
synchronized (mCachedAppOptimizer) {
app.mSetAdjForCompact = app.setAdj;
}
}
...
//或者防止应用在系统低内存的时候被回收,小于Android11,低版本代码位置
./frameworks/base/services/java/com/android/server/am/ActivityManagerService.java
private final boolean applyOomAdjLocked(ProcessRecord app, boolean wasKeeping,
ProcessRecord TOP_APP, boolean doingAll, boolean
reportingProcessState, long now) {
boolean success = true;
if (app.curRawAdj != app.setRawAdj) {
if (wasKeeping && !app.keeping) {
// This app is no longer something we want to keep. Note
// its current wake lock time to later know to kill it if
// it is not behaving well.
BatteryStatsImpl stats = mBatteryStatsService.getActiveStatistics();
synchronized (stats) {
app.lastWakeTime = stats.getProcessWakeTime(app.info.uid,
app.pid, SystemClock.elapsedRealtime());
}
app.lastCpuTime = app.curCpuTime;
}
app.setRawAdj = app.curRawAdj;
}
//add to writelist start
if ("com.xxx.xx".equals(app.processName)) {
app.curAdj = ProcessList.FOREGROUND_APP_ADJ;
}
//add to writelist start
if (app.curAdj != app.setAdj) {
if (Process.setOomAdj(app.pid, app.curAdj)) {
if (DEBUG_SWITCH || DEBUG_OOM_ADJ) Slog.v(
TAG, "Set " + app.pid + " " + app.processName +
" adj " + app.curAdj + ": " + app.adjType);
app.setAdj = app.curAdj
} else {
success = false;
Slog.w(TAG, "Failed setting oom adj of " + app + " to " + app.curAdj);
}
}
...
}
//关于低内存
adb shell dumpsys meminfo 查看机器内存消耗
Total RAM: 2,004,808K (status normal)
(剩余)Free RAM: 1,023,528K ( 322,280K cached pss + 600,996K cached kernel + 100,252K free)
ION: 25,252K ( 18,768K mapped + 0K unmapped + 6,484K pools)
Used RAM: 979,670K ( 794,862K used pss + 184,808K kernel)
(被占用)Lost RAM: 80,180K
ZRAM: 34,768K physical used for 116,992K in swap (1,002,400K total swap)
Tuning: 192 (large 512), oom 322,560K, restore limit 107,520K (high-end-gfx)
LMKD是一个进程，它监视正在运行的Android系统的内存状态，并通过杀死最不重要的进程(es)来应对高内存压力，从而使系统的性能保持在可接受的水平。
所有应用进程都是从zygote孵化出来的，记录在AMS中mLruProcesses列表中。
由AMS进行统一管理，AMS中会根据进程的状态更新进程对应的oom_adj值，这个值会通过文件传递到kernel中去，kernel有个低内存回收机制。
在内存达到一定阀值时会触发清理oom_adj值高的进程腾出更多的内存空间。
不同*_ADJ的有不同优先级，值越大优先级越低。
如何查看应用进程adj
adb shell
ps -A | grep xxx (查pid)
su
//查看minfree的值，安卓10以后没有目录/sys/module/lowmemorykiller/，待进一步分析
cat /sys/module/lowmemorykiller/parameters/minfree
//查看adj的值
cat /sys/module/lowmemorykiller/parameters/adj
//查看进程<pid>的adj值
cat /proc/<pid>/oom_adj
cat /proc/<pid>/oom_score_adj
Android11 开机第一次Launcher启动流程代码_android 系统开机启动 拉起进程 源码
【Android】Android Framework系列--Launcher3各启动场景源码分析_launcher3源码分析
Android app是如何杀掉的 - aspirs - 博客园 (cnblogs.com)
