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MultiFrameImageStreamCompleter null dereference #30340
Description
Got reports from the wild with the following stack trace:
2019-04-01 20:27:21.453 8085-8351/com.example.myapp I/flutter: ══╡ EXCEPTION CAUGHT BY SCHEDULER LIBRARY ╞═════════════════════════════════════════════════════════
2019-04-01 20:27:21.474 8085-8351/com.example.myapp I/flutter: The following NoSuchMethodError was thrown during a scheduler callback:
2019-04-01 20:27:21.475 8085-8351/com.example.myapp I/flutter: The getter 'image' was called on null.
2019-04-01 20:27:21.475 8085-8351/com.example.myapp I/flutter: Receiver: null
2019-04-01 20:27:21.475 8085-8351/com.example.myapp I/flutter: Tried calling: image
2019-04-01 20:27:21.475 8085-8351/com.example.myapp I/flutter: When the exception was thrown, this was the stack:
2019-04-01 20:27:21.492 8085-8351/com.example.myapp I/flutter: #0 Object.noSuchMethod (dart:core/runtime/lib/object_patch.dart:50:5)
2019-04-01 20:27:21.493 8085-8351/com.example.myapp I/flutter: #1 MultiFrameImageStreamCompleter._handleAppFrame (package:flutter/src/painting/image_stream.dart:548:46)
2019-04-01 20:27:21.493 8085-8351/com.example.myapp I/flutter: #2 __DriverBinding&BindingBase&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1012:15)
2019-04-01 20:27:21.493 8085-8351/com.example.myapp I/flutter: #3 __DriverBinding&BindingBase&ServicesBinding&SchedulerBinding.handleBeginFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:928:11)
2019-04-01 20:27:21.493 8085-8351/com.example.myapp I/flutter: #4 __InternalLinkedHashMap&_HashVMBase&MapMixin&_LinkedHashMapMixin.forEach (dart:collection/runtime/lib/compact_hash.dart:367:8)
2019-04-01 20:27:21.493 8085-8351/com.example.myapp I/flutter: #5 __DriverBinding&BindingBase&ServicesBinding&SchedulerBinding.handleBeginFrame (package:flutter/src/scheduler/binding.dart:926:17)
2019-04-01 20:27:21.493 8085-8351/com.example.myapp I/flutter: #6 __DriverBinding&BindingBase&ServicesBinding&SchedulerBinding._handleBeginFrame (package:flutter/src/scheduler/binding.dart:856:5)
2019-04-01 20:27:21.493 8085-8351/com.example.myapp I/flutter: #10 _invoke1 (dart:ui/hooks.dart:233:10)
2019-04-01 20:27:21.493 8085-8351/com.example.myapp I/flutter: #11 _beginFrame (dart:ui/hooks.dart:172:3)
2019-04-01 20:27:21.493 8085-8351/com.example.myapp I/flutter: (elided 3 frames from package dart:async)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: This exception was thrown in the context of a scheduler callback. When the scheduler callback was
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: _registered_ (as opposed to when the exception was thrown), this was the stack:
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #0 new _FrameCallbackEntry.<anonymous closure> (package:flutter/src/scheduler/binding.dart:112:33)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #1 new _FrameCallbackEntry (package:flutter/src/scheduler/binding.dart:115:6)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #2 __DriverBinding&BindingBase&ServicesBinding&SchedulerBinding.scheduleFrameCallback (package:flutter/src/scheduler/binding.dart:448:49)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #3 MultiFrameImageStreamCompleter._decodeNextFrameAndSchedule (package:flutter/src/painting/image_stream.dart:592:31)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: <asynchronous suspension>
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #4 MultiFrameImageStreamCompleter._handleAppFrame (package:flutter/src/painting/image_stream.dart:554:9)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #5 __DriverBinding&BindingBase&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1012:15)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #6 __DriverBinding&BindingBase&ServicesBinding&SchedulerBinding.handleBeginFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:928:11)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #7 __InternalLinkedHashMap&_HashVMBase&MapMixin&_LinkedHashMapMixin.forEach (dart:collection/runtime/lib/compact_hash.dart:367:8)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #8 __DriverBinding&BindingBase&ServicesBinding&SchedulerBinding.handleBeginFrame (package:flutter/src/scheduler/binding.dart:926:17)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #9 __DriverBinding&BindingBase&ServicesBinding&SchedulerBinding._handleBeginFrame (package:flutter/src/scheduler/binding.dart:856:5)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #13 _invoke1 (dart:ui/hooks.dart:233:10)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: #14 _beginFrame (dart:ui/hooks.dart:172:3)
2019-04-01 20:27:21.505 8085-8351/com.example.myapp I/flutter: (elided 3 frames from package dart:async)
After some analysis of the code I see how this can happen if _handleAppFrame is added multiple times as a frame callback. 2 ways in which this can happen:
Scenario 1
- A GIF frame is decoded and a Flutter frame is executed before it's time to show the next GIF frame.
- The timer that's waiting for enough time to elapse is invoked, and schedules a callback for the next Flutter frame(here).
- Before the next Flutter frame is executed,
MultiFrameImageStreamCompleter#removeListeneris called followed by ``MultiFrameImageStreamCompleter#addListenerthat is invoking_decodeNextFrameAndSchedule` which is adding `_handleAppFrame` again as a next frame callback.
Scenario 2
removeListener and addListener are called multiple times in succession, every call to addListener can result in another registration of _handleAppFrame to the next Flutter frame callbacks list.
Activity
github-actions commentedon Aug 30, 2021
This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of
flutter doctor -vand a minimal reproduction of the issue.Fix null _nextFrame in MultiFrameImageStreamCompleter._handleAppFrame…
Fix null _nextFrame in MultiFrameImageStreamCompleter._handleAppFrame…