fix(anr): Skip ANR profiling while a debugger is connected

CHANGELOG.md

@@ -12,6 +12,7 @@
 ### Improvements
 
 - Speed up Session Replay and screenshot masking for large `maskViewClasses`/`unmaskViewClasses` lists by using constant-time class lookups ([#6410](https://github.com/getsentry/sentry-java/pull/6410))
+- Skip ANR profiling while a debugger is connected ([#6389](https://github.com/getsentry/sentry-java/pull/6389))
 
 ### Fixes
 

sentry-android-core/api/sentry-android-core.api

@@ -736,6 +736,7 @@ public class io/sentry/android/core/anr/AnrProfilingIntegration : io/sentry/Inte
 	public fun close ()V
 	protected fun getProfileManager ()Lio/sentry/android/core/anr/AnrProfileManager;
 	protected fun getState ()Lio/sentry/android/core/anr/AnrProfilingIntegration$MainThreadState;
+	protected fun isDebuggerConnected ()Z
 	public fun onBackground ()V
 	public fun onForeground ()V
 	public fun register (Lio/sentry/IScopes;Lio/sentry/SentryOptions;)V

sentry-android-core/src/main/java/io/sentry/android/core/anr/AnrProfilingIntegration.java

@@ -2,6 +2,7 @@
 
 import static io.sentry.util.IntegrationUtils.addIntegrationToSdkVersion;
 
+import android.os.Debug;
 import android.os.Handler;
 import android.os.Looper;
 import android.os.SystemClock;
@@ -211,6 +212,15 @@ public void run() {
 
   @ApiStatus.Internal
   protected void checkMainThread(final @NotNull Thread mainThread) throws IOException {
+    if (isDebuggerConnected()) {
+      // The main thread can sit at a breakpoint for a long time, which is not an ANR. Reset the
+      // timestamp, so the paused time does not count against us after the debugger detaches.
+      mainThreadState = MainThreadState.IDLE;
+      sampled = false;
+      updater.run();
+      return;
+    }
+
     final long now = SystemClock.uptimeMillis();
     final long diff = now - lastMainThreadExecutionTime;
 
@@ -268,6 +278,11 @@ protected void checkMainThread(final @NotNull Thread mainThread) throws IOExcept
     }
   }
 
+  @ApiStatus.Internal
+  protected boolean isDebuggerConnected() {
+    return Debug.isDebuggerConnected();
+  }
+
   @TestOnly
   @NotNull
   protected MainThreadState getState() {

sentry-android-core/src/test/java/io/sentry/android/core/anr/AnrProfilingIntegrationTest.kt

@@ -196,6 +196,37 @@ class AnrProfilingIntegrationTest {
     assertEquals(AnrProfilingIntegration.MAX_NUM_STACKS, integration.numCollectedStacks.get())
   }
 
+  @Test
+  fun `debugger pauses are treated as idle`() {
+    val mainThread = Thread.currentThread()
+    SystemClock.setCurrentTimeMillis(1_000)
+
+    val androidOptions =
+      SentryAndroidOptions().apply {
+        cacheDirPath = tmpDir.root.absolutePath
+        setLogger(mockLogger)
+        anrProfilingSampleRate = 1.0
+      }
+
+    var debuggerConnected = true
+    val integration =
+      object : AnrProfilingIntegration() {
+        override fun isDebuggerConnected(): Boolean = debuggerConnected
+      }
+    integration.register(mockScopes, androidOptions)
+
+    SystemClock.setCurrentTimeMillis(20_000)
+    integration.checkMainThread(mainThread)
+    assertEquals(AnrProfilingIntegration.MainThreadState.IDLE, integration.state)
+    assertEquals(0, integration.numCollectedStacks.get())
+
+    // the time spent paused must not count towards an ANR once the debugger detaches
+    debuggerConnected = false
+    SystemClock.setCurrentTimeMillis(20_100)
+    integration.checkMainThread(mainThread)
+    assertEquals(AnrProfilingIntegration.MainThreadState.IDLE, integration.state)
+  }
+
   @Test
   fun `background foreground transitions don't trigger an ANR`() {
     val mainThread = Thread.currentThread()