sgl-project/sglang · error · ValueError

total_consumer_count must be positive

Error message

total_consumer_count must be positive

What it means

StreamOrderedConsumer initialization requires total_consumer_count > 0 because ready/ack bookkeeping allocates one slot per consumer. Zero or negative counts would make acknowledgement arithmetic and slot offsets invalid, so it fails fast with ValueError.

Source

Thrown at python/sglang/srt/multimodal/transport/memory_pool.py:93

            f"[0, {total_consumer_count})"
        )
    return rank


class StreamOrderedPoolConsumerMixin:
    """Ready/wait/ack protocol for stream-ordered GPU feature proxies."""

    def _init_stream_ordered_consumer(
        self,
        *,
        ready_byte_offset: int,
        ack_byte_offset: int,
        generation: int,
        total_consumer_count: int,
        transport_name: str,
    ) -> None:
        if total_consumer_count <= 0:
            raise ValueError("total_consumer_count must be positive")
        self.ready_byte_offset = ready_byte_offset
        self.ack_byte_offset = ack_byte_offset
        self.generation = generation
        self.total_consumer_count = total_consumer_count
        self.transport_name = transport_name
        self._consumer_acknowledged = False

    def _wait_until_ready(self, base_address: int, device_id: int) -> None:
        stream_wait_value32(
            device_id,
            base_address + self.ready_byte_offset,
            self.generation,
            self.transport_name,
        )

    def _acknowledge_on_stream(
        self,
        base_address: int,

View on GitHub (pinned to 0132848349)

Solutions

1. Ensure the tokenizer worker / consumer count is at least 1 before starting the server
2. Fix server args (--tokenizer-worker-num, --dp-size) so computed consumer count > 0
3. Delay transport construction until worker topology is resolved

Example fix

# before
_init_stream_ordered_consumer(..., total_consumer_count=0, ...)
# after
_init_stream_ordered_consumer(..., total_consumer_count=num_tokenizer_workers, ...)  # >=1

if total_consumer_count is None or total_consumer_count < 1:
    raise ValueError('consumer count must be >= 1')

When it happens

Trigger: Constructing the IPC transport (whose __init__ calls _init_stream_ordered_consumer) with total_consumer_count=0 — typically because the tokenizer worker count resolved to 0 at startup.

Common situations: Degenerate configs (dp=1 with 0 tokenizer workers computed), early-startup races where worker counts are not yet populated, or tests passing 0 explicitly.

Related errors

• total_pool_size must be positive
• tokenizer_worker_num must be positive
• memory_size must be positive
• consumer_count must be positive
• max_inflight_slices must be positive

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/7a15b1eb0305e969. Report an issue: GitHub.