OpenAL Music Crashes on LWJGL3

Issue details

Playing music on LWJGL3 crashes sometimes possibly due to synchronization issues.

How to reproduce

Based on my assessment, it’s possible for OpenALMusic.fill(…) to be called from multiple threads causing a buffer exception if 2+ threads manipulate tempBuffer at the same time. Attached is a player-submitted crash report. An example would be calling play from a non-render thread while the render-thread updates the audio at the same time.

Proposed solution

Maybe the easiest solution is to simply make the method synchronized:

private synchronized boolean fill (int bufferID) {
  ...
}

Version of LibGDX and/or relevant dependencies

libGDX 1.9.14 with LWJGL 3.2.3

Stacktrace

java.nio.BufferOverflowException
	at java.nio.DirectByteBuffer.put(DirectByteBuffer.java:362)
	at com.badlogic.gdx.backends.lwjgl3.audio.OpenALMusic.fill(OpenALMusic.java:269)
	at com.badlogic.gdx.backends.lwjgl3.audio.OpenALMusic.update(OpenALMusic.java:237)
	at com.badlogic.gdx.backends.lwjgl3.audio.OpenALLwjgl3Audio.update(OpenALLwjgl3Audio.java:250)
	at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application.loop(Lwjgl3Application.java:133)
	at com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application.<init>(Lwjgl3Application.java:117)

Please select the affected platforms

• Android
• iOS
• HTML/GWT
• Desktop with LWJGL3

[mgsx-dev]

@noblemaster ah yeah, you’re right about the loading case (or any other cases where GLThread is busy). I’d be happy to have music update/fill in a separated thread. +1 for that change.

[noblemaster]

Pull Request is here: https://github.com/libgdx/libgdx/pull/6452