ActivityManagerService.appNotResponding()在程序无响应、ANR时被调用，分析这个函数有有助于更好地理解日志中打印出的信息。
final void appNotResponding(ProcessRecord app, ActivityRecord activity,
ActivityRecord parent, boolean aboveSystem, final String annotation) {
ArrayList<Integer> firstPids = new ArrayList<Integer>(5);
SparseArray<Boolean> lastPids = new SparseArray<Boolean>(20);
if (mController != null) {
try {
// 0 == continue, -1 = kill process immediately
int res = mController.appEarlyNotResponding(app.processName, app.pid, annotation);
if (res < 0 && app.pid != MY_PID) Process.killProcess(app.pid);
} catch (RemoteException e) {
mController = null;
Watchdog.getInstance().setActivityController(null);
}
}
long anrTime = SystemClock.uptimeMillis();
if (MONITOR_CPU_USAGE) {
updateCpuStatsNow();
}
synchronized (this) {
// PowerManager.reboot() can block for a long time, so ignore ANRs while shutting down.
if (mShuttingDown) { //如果系统正在关机，ANR不处理，return；
Slog.i(TAG, "During shutdown skipping ANR: " + app + " " + annotation);
return;
} else if (app.notResponding) { //如果之前已经报过该进程ANR了，那么不再执行下面的逻辑，直接打印“<span style="font-family: Arial, Helvetica, sans-serif;">Skipping duplicate ANR“，然后return；</span>
”
Slog.i(TAG, "Skipping duplicate ANR: " + app + " " + annotation);
return;
} else if (app.crashing) { //如果应用发生crash，此时ANR忽略掉，return；
Slog.i(TAG, "Crashing app skipping ANR: " + app + " " + annotation);
return;
}
// In case we come through here for the same app before completing
// this one, mark as anring now so we will bail out.
app.notResponding = true; //将<span style="font-family: Arial, Helvetica, sans-serif;">notResponding 设为true，表示已经在处理该进程的ANR，下次再报ANR直接return；</span>
// Log the ANR to the event log.
EventLog.writeEvent(EventLogTags.AM_ANR, app.userId, app.pid, //往event日志中写AM_ANR信息，全局搜索了下，只有这一个地方打印event ANR日志，那么如果event日志中有此日志项，就说明已经走进这个函数逻辑里面了；
app.processName, app.info.flags, annotation);
// Dump thread traces as quickly as we can, starting with "interesting" processes.
firstPids.add(app.pid); //将出ANR的进程加入<span style="font-family: Arial, Helvetica, sans-serif;">firstPids列表，后续打印该进程的trace；</span>
int parentPid = app.pid;
if (parent != null && parent.app != null && parent.app.pid > 0) parentPid = parent.app.pid; //将父进程也加入<span style="font-family: Arial, Helvetica, sans-serif;">firstPids列表；</span>
if (parentPid != app.pid) firstPids.add(parentPid);
if (MY_PID != app.pid && MY_PID != parentPid) firstPids.add(MY_PID); //将system_server进程加入<span style="font-family: Arial, Helvetica, sans-serif;">firstPids列表，说明每次ANR的trace中必然包括system_server进程的trace；</span>
for (int i = mLruProcesses.size() - 1; i >= 0; i--) {
ProcessRecord r = mLruProcesses.get(i);
if (r != null && r.thread != null) {
int pid = r.pid;
if (pid > 0 && pid != app.pid && pid != parentPid && pid != MY_PID) {
if (r.persistent) {
firstPids.add(pid); //将常驻进程也加入<span style="font-family: Arial, Helvetica, sans-serif;">firstPids列表中；</span>
} else {
lastPids.put(pid, Boolean.TRUE);
}
}
}
}
}
// Log the ANR to the main log.
StringBuilder info = new StringBuilder();
info.setLength(0);
info.append("ANR in ").append(app.processName); //"ANR in"也是分析ANR的关键日志；
if (activity != null && activity.shortComponentName != null) {
info.append(" (").append(activity.shortComponentName).append(")");
}
info.append("\n");
info.append("PID: ").append(app.pid).append("\n");
if (annotation != null) {
info.append("Reason: ").append(annotation).append("\n");
}
if (parent != null && parent != activity) {
info.append("Parent: ").append(parent.shortComponentName).append("\n");
}
final ProcessCpuTracker processCpuTracker = new ProcessCpuTracker(true);
File tracesFile = dumpStackTraces(true, firstPids, processCpuTracker, lastPids,
NATIVE_STACKS_OF_INTEREST);
String cpuInfo = null;
if (MONITOR_CPU_USAGE) {
updateCpuStatsNow();
synchronized (mProcessCpuThread) {
cpuInfo = mProcessCpuTracker.printCurrentState(anrTime);
}
info.append(processCpuTracker.printCurrentLoad());
info.append(cpuInfo);
}
info.append(processCpuTracker.printCurrentState(anrTime));
Slog.e(TAG, info.toString());
if (tracesFile == null) { //如果调用<span style="font-family: Arial, Helvetica, sans-serif;">dumpStackTraces没有生存trace，那么重新只打印ANR进程trace；</span>
// There is no trace file, so dump (only) the alleged culprit's threads to the log
Process.sendSignal(app.pid, Process.SIGNAL_QUIT);
}
addErrorToDropBox("anr", app, app.processName, activity, parent, annotation, //将trace文件加入DropBox中，这么说来只要发生ANR，并在日志中有"ANR in"，那么在DropBox中必然有一份trace日志，命名已‘ANR’形式；
cpuInfo, tracesFile, null);
if (mController != null) {
try {
// 0 == show dialog, 1 = keep waiting, -1 = kill process immediately
int res = mController.appNotResponding(app.processName, app.pid, info.toString());
if (res != 0) {
if (res < 0 && app.pid != MY_PID) {
Process.killProcess(app.pid);
} else {
synchronized (this) {
mServices.scheduleServiceTimeoutLocked(app);
}
}
return;
}
} catch (RemoteException e) {
mController = null;
Watchdog.getInstance().setActivityController(null);
}
}
// Unless configured otherwise, swallow ANRs in background processes & kill the process.
boolean showBackground = Settings.Secure.getInt(mContext.getContentResolver(),
Settings.Secure.ANR_SHOW_BACKGROUND, 0) != 0;
synchronized (this) {
if (!showBackground && !app.isInterestingToUserLocked() && app.pid != MY_PID) {
killUnneededProcessLocked(app, "background ANR");
return;
}
// Set the app's notResponding state, and look up the errorReportReceiver
makeAppNotRespondingLocked(app,
activity != null ? activity.shortComponentName : null,
annotation != null ? "ANR " + annotation : "ANR",
info.toString());
// Bring up the infamous App Not Responding dialog
Message msg = Message.obtain();
HashMap<String, Object> map = new HashMap<String, Object>();
msg.what = SHOW_NOT_RESPONDING_MSG;
msg.obj = map;
msg.arg1 = aboveSystem ? 1 : 0;
map.put("app", app);
if (activity != null) {
map.put("activity", activity);
}
mHandler.sendMessage(msg);
}
}
原文：http://blog.csdn.net/guoqifa29/article/details/42778089