Merge "Resolve Thread Visibility Issue in ProcessErrorStateRecord.appNotResponding" into udc-qpr-dev am: 52f45340a9

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23766528

Change-Id: I4cc8efb4252354001abcfcbc25e0eea3bbf79bcc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

services/core/java/com/android/server/am/ProcessErrorStateRecord.java

@@ -51,11 +51,11 @@ import android.util.SparseBooleanArray;
 import com.android.internal.annotations.CompositeRWLock;
 import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
-import com.android.modules.expresslog.Counter;
 import com.android.internal.os.ProcessCpuTracker;
 import com.android.internal.os.TimeoutRecord;
 import com.android.internal.os.anr.AnrLatencyTracker;
 import com.android.internal.util.FrameworkStatsLog;
+import com.android.modules.expresslog.Counter;
 import com.android.server.ResourcePressureUtil;
 import com.android.server.criticalevents.CriticalEventLog;
 import com.android.server.stats.pull.ProcfsMemoryUtil.MemorySnapshot;
@@ -456,6 +456,11 @@ class ProcessErrorStateRecord {
         String currentPsiState = ResourcePressureUtil.currentPsiState();
         latencyTracker.currentPsiStateReturned();
         report.append(currentPsiState);
+        // The 'processCpuTracker' variable is a shared resource that might be initialized and
+        // updated in a different thread. In order to prevent thread visibility issues, which
+        // can occur when one thread does not immediately see the changes made to
+        // 'processCpuTracker' by another thread, it is necessary to use synchronization whenever
+        // 'processCpuTracker' is accessed or modified.
         ProcessCpuTracker processCpuTracker = new ProcessCpuTracker(true);
 
         // We push the native pids collection task to the helper thread through
@@ -517,12 +522,16 @@ class ProcessErrorStateRecord {
             }
             mService.updateCpuStatsNow();
             mService.mAppProfiler.printCurrentCpuState(report, anrTime);
-            info.append(processCpuTracker.printCurrentLoad());
+            synchronized (processCpuTracker) {
+                info.append(processCpuTracker.printCurrentLoad());
+            }
             info.append(report);
         }
         report.append(tracesFileException.getBuffer());
 
-        info.append(processCpuTracker.printCurrentState(anrTime));
+        synchronized (processCpuTracker) {
+            info.append(processCpuTracker.printCurrentState(anrTime));
+        }
 
         Slog.e(TAG, info.toString());
         if (tracesFile == null) {

services/core/java/com/android/server/am/StackTracesDumpHelper.java

@@ -464,28 +464,31 @@ public class StackTracesDumpHelper {
             latencyTracker.processCpuTrackerMethodsCalled();
         }
         ArrayList<Integer> extraPids = new ArrayList<>();
-        processCpuTracker.init();
+        synchronized (processCpuTracker) {
+            processCpuTracker.init();
+        }
         try {
             Thread.sleep(200);
         } catch (InterruptedException ignored) {
         }
 
-        processCpuTracker.update();
+        synchronized (processCpuTracker) {
+            processCpuTracker.update();
+            // We'll take the stack crawls of just the top apps using CPU.
+            final int workingStatsNumber = processCpuTracker.countWorkingStats();
+            for (int i = 0; i < workingStatsNumber && extraPids.size() < 2; i++) {
+                ProcessCpuTracker.Stats stats = processCpuTracker.getWorkingStats(i);
+                if (lastPids.indexOfKey(stats.pid) >= 0) {
+                    if (DEBUG_ANR) {
+                        Slog.d(TAG, "Collecting stacks for extra pid " + stats.pid);
+                    }
 
-        // We'll take the stack crawls of just the top apps using CPU.
+                    extraPids.add(stats.pid);
-        final int workingStatsNumber = processCpuTracker.countWorkingStats();
+                } else {
-        for (int i = 0; i < workingStatsNumber && extraPids.size() < 2; i++) {
+                    Slog.i(TAG,
-            ProcessCpuTracker.Stats stats = processCpuTracker.getWorkingStats(i);
+                            "Skipping next CPU consuming process, not a java proc: "
-            if (lastPids.indexOfKey(stats.pid) >= 0) {
+                            + stats.pid);
-                if (DEBUG_ANR) {
-                    Slog.d(TAG, "Collecting stacks for extra pid " + stats.pid);
                 }
-
-                extraPids.add(stats.pid);
-            } else {
-                Slog.i(TAG,
-                        "Skipping next CPU consuming process, not a java proc: "
-                        + stats.pid);
             }
         }
         if (latencyTracker != null) {