I m updating a SnapshotStateList from a CoroutineScope and a

Question

I m updating a SnapshotStateList from a CoroutineScope and also reading same list from Composable `val list = SnapshotStateList lt VoiceItem gt ` `appScope launch ` `voicesList add VoiceItem id ` ` ` But i m getting a lot of ANR in production app like this ``````

Shakil Karim · Answer

``` at androidx compose runtime snapshots SnapshotStateList$StateListStateRecord assign SnapshotStateList kt 458 The main thread is blocked here It is waiting trying to acquire lock 0x0de00d89 java lang Object held by thread 23 at androidx compose runtime snapshots SnapshotKt overwriteUnusedRecordsLocked Snapshot kt 1941 at androidx compose runtime snapshots SnapshotKt advanceGlobalSnapshot Snapshot kt 1773 at androidx compose runtime snapshots SnapshotKt advanceGlobalSnapshot Snapshot kt at androidx compose runtime snapshots SnapshotKt access$advanceGlobalSnapshot Snapshot kt at androidx compose runtime snapshots Snapshot$Companion sendApplyNotifications Snapshot kt 568 at androidx compose ui platform GlobalSnapshotManager$ensureStarted$1 invokeSuspend GlobalSnapshotManager android kt 46 at kotlin coroutines jvm internal BaseContinuationImpl resumeWith ContinuationImpl kt 33 at kotlinx coroutines DispatchedTask run DispatchedTask kt 106 at androidx compose ui platform AndroidUiDispatcher performTrampolineDispatch AndroidUiDispatcher android kt 81 at androidx compose ui platform AndroidUiDispatcher access$performTrampolineDispatch AndroidUiDispatcher android kt 41 at androidx compose ui platform AndroidUiDispatcher$dispatchCallback$1 run AndroidUiDispatcher android kt 57 at android os Handler handleCallback Handler java 938 at android os Handler dispatchMessage Handler java 99 at android os Looper loop Looper java 268 at android app ActivityThread main ActivityThread java 8017 at java lang reflect Method invoke Native method ```

Zach Klippenstein (he/him) [MOD] · Answer

Please file a bug Cc < Chuck Jazdzewski G >

Chuck Jazdzewski [G] · Answer

Can you include the thread 23 stack as well if you have it

Chuck Jazdzewski [G] · Answer

Inspecting the code it looks likely that the threads will deadlock in `conditionalUpdate` in the `synchronized` call on around line 204 Is what you are seeing then I believe the code can be fixed by moving the `synchronized` call inside the `writable` call both in `conditionalUpdate` and `mutate` which would have a a similar issue

Chuck Jazdzewski [G] · Answer

Never mind about the thread 23 request above I see you included the equivalent in 269402895

Shakil Karim · Answer

i have this stack related to Thread 23 ``` Timer 0 tid=23 Waiting at java lang Object wait Native method at java lang Object wait Object java 442 at java lang Object wait Object java 568 at java util TimerThread mainLoop Timer java 533 at java util TimerThread run Timer java 512 ```

Chuck Jazdzewski [G] · Answer

aosp 2528169 should address this I will requiest this being cherry picked into 1 4 after it lands in android main