Semaphore Leak Warning on Python 3.13.7 with Kokoro TTS in Async Context

[Mohammed-Yasin-Mulla]

Environment

• mlx-audio: v0.2.5
• Model: mlx-community/Kokoro-82M-bf16
• Python: 3.13.7
• Machine: MacBook Pro M3 Pro (18GB RAM)
• OS: macOS 26.0.1

Issue

Getting persistent semaphore leak warnings from Python's resource_tracker when using mlx-audio for real-time TTS:

INFO:whisperlivekit.audio_processor:internal_buffer=0.00s | lag=0.29s |
/Users/mohammedyasinmulla/.local/share/uv/python/cpython-3.13.7-macos-aarch64-none/lib/python3.13/multiprocessing/resource_tracker.py:324: UserWarning: resource_tracker: There appear to be 1 leaked semaphore objects to clean up at shutdown: {'/loky-12097-8myixz42'}

When it occurs:

• At first audio generation (client connection)

Attempted Fixes

1. ✅ Set LOKY_MAX_CPU_COUNT=1 → Reduced warnings but still appear occasionally
2. ✅ Explicit loky cleanup:

   from joblib.externals.loky import get_reusable_executor
   executor = get_reusable_executor(max_workers=None, timeout=1)
   executor.shutdown(wait=True, kill_workers=True)
   

3. ✅ Aggressive GC → Minimal impact
4. ✅ Force CPU mode (disabled MPS) → Improved stability, warnings persist

Questions

1. Does mlx-audio use joblib internally? (I see it's in dependencies)
2. Is there a recommended async pattern for long-running services?
3. Are there known Python 3.13.7 compatibility issues?
4. Does model.generate() spawn background processes?
5. Proper cleanup procedure for MLX models in async context?

Related:

• Also using mlx-whisper (via WhisperLiveKit) in same process
• Both may involve joblib/loky → cumulative effect?

[Blaizzy]

Hey @Mohammed-Yasin-Mulla

Could you provide a reproducible example?

Also, we have whisper support in mlx-audio.

Finally, leaked semaphore means that a process is consuming all your memory, maybe it's mlx-whisper + whisperLivekit combo.

[Mohammed-Yasin-Mulla]

Hey @Blaizzy Please check my repo: https://github.com/Mohammed-Yasin-Mulla/Local-Voice-AI/tree/mlx-audio In the mlx-audio branch

This sometimes randomly works out of the blue, and most of the time gives me this error above.

[Blaizzy]

Hey @Mohammed-Yasin-Mulla

This code base is vast, it would help and be much faster if you could pinpoint the issue for me to investigate.

I don’t know where to start as I’m not familiar with it.