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fix: normalise logits_processors None to [] to avoid mlx-lm crash (#934) #1747

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Merged
jundot merged 1 commit into from
Jun 9, 2026
+11 −2
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fix: normalise logits_processors None to [] to avoid mlx-lm crash (#934) #1747

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13 changes: 11 additions & 2 deletions omlx/scheduler.py
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Original file line number Diff line number Diff line change
Expand Up @@ -385,6 +385,13 @@ def _patched_generation_batch_step(self):
deltas = [model._uid_rope_deltas.get(uid, 0.0) for uid in self.uids]
model.set_batch_rope_deltas(mx.array(deltas))

# Defensive: mlx-lm's GenerationBatch._step does `any(self.logits_processors)`
# and `for p in self.logits_processors[e]`, both of which crash when
# logits_processors is None. Normalise to [] so the original code path
# works without modification. See #934.
if self.logits_processors is None:
self.logits_processors = []

result = _original_generation_batch_step(self)

# self._next_tokens contains the just-sampled tokens (async eval pending).
Expand Down Expand Up @@ -571,7 +578,9 @@ def _patched_ppb_split(self, indices):
new_batch.prefill_step_size = self.prefill_step_size
new_batch.samplers = self.samplers
new_batch.fallback_sampler = self.fallback_sampler
new_batch.logits_processors = self.logits_processors
# Defensive: normalise None → [] to avoid mlx-lm crash in _step
lps = self.logits_processors if self.logits_processors is not None else []
new_batch.logits_processors = lps
new_batch.state_machines = self.state_machines
new_batch.max_tokens = self.max_tokens

Expand Down Expand Up @@ -2030,7 +2039,7 @@ def _create_batch_generator(
max_tokens=sampling_params.max_tokens,
stop_tokens=stop_tokens_seq,
sampler=sampler,
logits_processors=logits_processors if logits_processors else None,
logits_processors=logits_processors if logits_processors else [],
prefill_batch_size=1,
completion_batch_size=self.config.completion_batch_size,
prefill_step_size=self.config.prefill_step_size,
Expand Down