Runs the A11yManagerService package monitor on a dedicated thread.

The default BackgroundThread used by PackageMonitor is shared by
other components and can get busy, causing a delay and eventual
ANR when responding to broadcasts sent to this PackageMonitor.

Fix: 348138695
Test: existing tests in `atest AccessibilityManagerService`
Test: install and uninstall packages, observe no change in behavior
Flag: com.android.server.accessibility.package_monitor_dedicated_thread
Change-Id: Idd112cfeb7e3e55d18d4596c28a90450aa72f682

2 files changed, 24 insertions, 1 deletions

diff --git a/services/accessibility/accessibility.aconfig b/services/accessibility/accessibility.aconfig
index ee3bbcaf711d..1280a048ed32 100644
--- a/services/accessibility/accessibility.aconfig
+++ b/services/accessibility/accessibility.aconfig
@@ -172,6 +172,16 @@ flag {
 }
 
 flag {
+    name: "package_monitor_dedicated_thread"
+    namespace: "accessibility"
+    description: "Runs the A11yManagerService PackageMonitor on a dedicated thread"
+    bug: "348138695"
+    metadata {
+        purpose: PURPOSE_BUGFIX
+    }
+}
+
+flag {
     name: "manager_package_monitor_logic_fix"
     namespace: "accessibility"
     description: "Corrects the return values of the HandleForceStop function"
diff --git a/services/accessibility/java/com/android/server/accessibility/AccessibilityManagerService.java b/services/accessibility/java/com/android/server/accessibility/AccessibilityManagerService.java
index d595d02016e0..a23eb6748481 100644
--- a/services/accessibility/java/com/android/server/accessibility/AccessibilityManagerService.java
+++ b/services/accessibility/java/com/android/server/accessibility/AccessibilityManagerService.java
@@ -116,6 +116,7 @@ import android.os.Binder;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
+import android.os.HandlerThread;
 import android.os.IBinder;
 import android.os.Looper;
 import android.os.Message;
@@ -901,7 +902,19 @@ public class AccessibilityManagerService extends IAccessibilityManager.Stub
     private void registerBroadcastReceivers() {
         // package changes
         mPackageMonitor = new ManagerPackageMonitor(this);
-        mPackageMonitor.register(mContext, null,  UserHandle.ALL, true);
+        final Looper packageMonitorLooper;
+        if (Flags.packageMonitorDedicatedThread()) {
+            // Use a dedicated thread because the default BackgroundThread used by PackageMonitor
+            // is shared by other components and can get busy, causing a delay and eventual ANR when
+            // responding to broadcasts sent to this PackageMonitor.
+            HandlerThread packageMonitorThread = new HandlerThread(LOG_TAG + " PackageMonitor",
+                    Process.THREAD_PRIORITY_BACKGROUND);
+            packageMonitorThread.start();
+            packageMonitorLooper = packageMonitorThread.getLooper();
+        } else {
+            packageMonitorLooper = null;
+        }
+        mPackageMonitor.register(mContext, packageMonitorLooper,  UserHandle.ALL, true);
 
         // user change and unlock
         IntentFilter intentFilter = new IntentFilter();