fix(replay): Dispatch session-deadline stop off the replay worker thread

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Fixes
 
+- Fix background ANR when a session replay reaches its duration deadline: the resulting `stop()` (and its segment encoding) no longer runs on the replay worker thread while holding the replay lifecycle lock, which could block a foreground `start()` on the main thread ([#5826](https://github.com/getsentry/sentry-java/pull/5826))
 - Pin the published Sentry Android SDK's AAR metadata `minCompileSdk` to our `minSdk` (`21`) instead of AGP 9's new default of the SDK's own `compileSdk` (`37`), so apps that depend on the SDK aren't forced to raise their `compileSdk` ([#5823](https://github.com/getsentry/sentry-java/pull/5823))
 
 ### Performance

sentry-android-replay/src/main/java/io/sentry/android/replay/capture/SessionCaptureStrategy.kt

@@ -10,6 +10,7 @@ import io.sentry.android.replay.ReplayCache
 import io.sentry.android.replay.ScreenshotRecorderConfig
 import io.sentry.android.replay.capture.CaptureStrategy.ReplaySegment
 import io.sentry.android.replay.util.ReplayRunnable
+import io.sentry.android.replay.util.submitSafely
 import io.sentry.protocol.SentryId
 import io.sentry.transport.ICurrentDateProvider
 import io.sentry.util.FileUtils
@@ -134,8 +135,13 @@ internal class SessionCaptureStrategy(
         }
 
         if ((now - replayStartTimestamp.get() >= options.sessionReplay.sessionDuration)) {
-          options.replayController.stop()
           options.logger.log(INFO, "Session replay deadline exceeded (1h), stopping recording")
+          // dispatch off the replay worker thread, otherwise stop() would run the final segment
+          // encoding synchronously while holding the replay lifecycle lock, blocking a foreground
+          // start() on the main thread (ANR)
+          options.executorService.submitSafely(options, "$TAG.stop") {
+            options.replayController.stop()
+          }
         }
       }
     )

sentry-android-replay/src/test/java/io/sentry/android/replay/capture/SessionCaptureStrategyTest.kt

@@ -29,6 +29,8 @@ import io.sentry.protocol.SentryId
 import io.sentry.rrweb.RRWebBreadcrumbEvent
 import io.sentry.rrweb.RRWebMetaEvent
 import io.sentry.rrweb.RRWebOptionsEvent
+import io.sentry.test.DeferredExecutorService
+import io.sentry.test.ImmediateExecutorService
 import io.sentry.transport.CurrentDateProvider
 import io.sentry.transport.ICurrentDateProvider
 import java.io.File
@@ -66,6 +68,7 @@ class SessionCaptureStrategyTest {
         setReplayController(
           mock { on { breadcrumbConverter }.thenReturn(DefaultReplayBreadcrumbConverter()) }
         )
+        executorService = ImmediateExecutorService()
       }
     val scope = Scope(options)
     val scopes =
@@ -291,6 +294,35 @@ class SessionCaptureStrategyTest {
     verify(fixture.options.replayController).stop()
   }
 
+  @Test
+  fun `onScreenshotRecorded dispatches deadline stop off the calling thread`() {
+    val deferredExecutor = DeferredExecutorService()
+    fixture.options.executorService = deferredExecutor
+    var count = 0
+    val strategy =
+      fixture.getSut(
+        dateProvider = {
+          if (count++ == 2) {
+            System.currentTimeMillis() + (fixture.options.sessionReplay.sessionDuration * 2)
+          } else {
+            System.currentTimeMillis()
+          }
+        }
+      )
+    strategy.start()
+    strategy.onConfigurationChanged(mock<ScreenshotRecorderConfig>())
+
+    strategy.onScreenshotRecorded(mock<Bitmap>()) {}
+
+    // stop must not run inline on the caller (replay worker) thread, otherwise it would encode the
+    // final segment while holding the lifecycle lock and block a foreground start() (ANR)
+    verify(fixture.options.replayController, never()).stop()
+
+    deferredExecutor.runAll()
+
+    verify(fixture.options.replayController).stop()
+  }
+
   @Test
   fun `onConfigurationChanged creates new segment and updates config`() {
     val strategy = fixture.getSut()