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Commit e495b37e authored by Mohamad Mahmoud's avatar Mohamad Mahmoud
Browse files

Resolve Thread Visibility Issue in ProcessErrorStateRecord.appNotResponding 

Use processCpuTracker as an intrinsic lock to correct a thread visibility
issue within the ProcessErrorStateRecord.appNotResponding method. This ensures
proper synchronization and prevents potential ANR dumping errors due to
concurrent access.

Test: Tested manually
Bug: 278852424
Change-Id: I93e394e7da90ed1ad23b11b36c775f648ccfdb63
parent d6ac3603

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

+12 −3
Original line number Diff line number Diff line
@@ -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);

            synchronized (processCpuTracker) {

                info.append(processCpuTracker.printCurrentLoad());

            }

            info.append(report);

        }

        report.append(tracesFileException.getBuffer());



        synchronized (processCpuTracker) {

            info.append(processCpuTracker.printCurrentState(anrTime));

        }



        Slog.e(TAG, info.toString());

        if (tracesFile == null) {

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

+18 −15
Original line number Diff line number Diff line
@@ -464,14 +464,16 @@ public class StackTracesDumpHelper { 
            latencyTracker.processCpuTrackerMethodsCalled();

        }

        ArrayList<Integer> extraPids = new ArrayList<>();

        synchronized (processCpuTracker) {

            processCpuTracker.init();

        }

        try {

            Thread.sleep(200);

        } catch (InterruptedException ignored) {

        }



        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++) {
@@ -488,6 +490,7 @@ public class StackTracesDumpHelper { 
                            + stats.pid);

                }

            }

        }

        if (latencyTracker != null) {

            latencyTracker.processCpuTrackerMethodsReturned();

        }