rohitg00/ai-engineering-from-scratch · error · ValueError

rank cannot send to itself

Error message

rank cannot send to itself

What it means

Error "rank cannot send to itself" thrown in rohitg00/ai-engineering-from-scratch.

Source

Thrown at phases/19-capstone-projects/76-collective-ops-from-scratch/code/main.py:55

@dataclass
class Mesh:
    """A point-to-point mesh wired as a fully-connected graph of queues.

    Each rank holds out_queues[dst] and in_queues[src]. The ring algorithms
    only use neighbour edges; the full mesh keeps the API general so future
    lessons can experiment with tree topologies without rewiring.
    """

    rank: int
    world_size: int
    out_queues: list
    in_queues: list
    byte_counter: object = None

    def send(self, dst: int, tensor: torch.Tensor) -> None:
        if dst == self.rank:
            raise ValueError("rank cannot send to itself")
        payload = tensor.detach().clone().contiguous()
        nbytes = payload.numel() * payload.element_size()
        if self.byte_counter is not None:
            with self.byte_counter.get_lock():
                self.byte_counter.value += nbytes
        self.out_queues[dst].put(payload)

    def recv(self, src: int) -> torch.Tensor:
        if src == self.rank:
            raise ValueError("rank cannot recv from itself")
        return self.in_queues[src].get(timeout=RECV_TIMEOUT_S)


def build_queue_grid(ctx, world_size: int):
    """Allocate a (world_size, world_size) grid of queues using the given context."""
    grid = [[None] * world_size for _ in range(world_size)]
    for src in range(world_size):
        for dst in range(world_size):

View on GitHub (pinned to 39ea8a1c6d)

When it happens

Trigger: Thrown at phases/19-capstone-projects/76-collective-ops-from-scratch/code/main.py:55 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of rohitg00/ai-engineering-from-scratch@39ea8a1c6d (2026-08-26). Data as JSON: /api/errors/0759a02151001882. Report an issue: GitHub.