Android platform OutOfMemory crash

[tiktiger852]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

os version: android 10
alphatab version: v1.3.0/v1.4.0

https://github.com/CoderLine/alphaTabSamplesAndroid

When playing 'canon.gp', the app crashes later, and the Android logcat shows an 'OutOfMemory' error,

logcat:
FATAL EXCEPTION: alphaSynthWorkerThread
Process: net.alphatab.android.sample, PID: 2925
java.lang.StackOverflowError: stack size 1039KB
at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:241)
at java.util.ArrayList.add(ArrayList.java:485)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)

..........
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.ArrayList$SubList.add(ArrayList.java:1066)
at java.util.AbstractList.add(AbstractList.java:108)
2025-03-17 17:11:11.558 2925-2975 AndroidRuntime net.alphatab.android.sample E at alphaTab.collections.List.push(List.kt:39)
at alphaTab.synth.ds.Queue.enqueue(Queue.kt:62)
at alphaTab.synth.synthesis.TinySoundFont.dispatchEvent(TinySoundFont.kt:165)
at alphaTab.synth.MidiFileSequencer.fillMidiEventQueueLimited(MidiFileSequencer.kt:294)
at alphaTab.synth.MidiFileSequencer.fillMidiEventQueue(MidiFileSequencer.kt:274)
at alphaTab.synth.AlphaSynth$2.invoke(AlphaSynth.kt:224)
at alphaTab.synth.AlphaSynth$2.invoke(AlphaSynth.kt:214)
at alphaTab.EventEmitter.trigger(EventEmitter.kt:64)
at alphaTab.platform.android.AndroidSynthOutput$onSampleRequest$1.invoke(AndroidSynthOutput.kt:97)
at alphaTab.platform.android.AndroidSynthOutput$onSampleRequest$1.invoke(AndroidSynthOutput.kt:96)
at alphaTab.platform.android.AndroidThreadAlphaSynthWorkerPlayer.run(AndroidThreadAlphaSynthWorkerPlayer.kt:74)

Expected Behavior

Fix this issue

Steps To Reproduce

1.checkout out https://github.com/CoderLine/alphaTabSamplesAndroid,
2. build, then install it
3. open canon.gp and wait for the problem to appear.

Link to jsFiddle, CodePen, Project

No response

Found in Version

1.3

Platform

Android (Native)

Environment

- **OS**:android 10

Anything else?

No response

[Danielku15]

Thanks for reporting. I'll need to look deeper here. Just from the callstack the error is inside Android/Java not alphaTab. It's a simple add of an item to a list which results in and endless recursion.

The most likely root cause is a multi-threading issue in this area of the Android platform code of alphaTab. Generally alphaTab expects a single-threaded (or thread-isolated) environment like in JavaScript.

[Danielku15]

@tiktiger852 Sorry for the delay. I tried to reproduce the issue but on 1.3.0 I cannot reproduce your problem. But I noticed a bunch of other problems in 1.4.0 which made the package unusable. They are fixed in 1.4.3.

I also tried to trace the code paths but could not see how a concurrent access to this queue could happen. In my tests (physical device and emulator) the problem never appeared.

Can you run some more tests on your side under what cicumstances the problem happens and try to give more insights in the steps to reproduce? Please also try with 1.4.3 (freshly published on Maven central).