pola-rs/polars · error · NotImplementedError

query monitoring is not supported by the GPU engine

Error message

query monitoring is not supported by the GPU engine

What it means

GPUEngine constructor guard: monitoring=True was requested, but the GPU engine has no query-monitoring facility, so __init__ raises immediately. Any truthy `monitoring` argument triggers it; it is a capability check, not a runtime failure.

Source

Thrown at py-polars/src/polars/lazyframe/engine.py:917

    back to the CPU engine.
    """
    config: Mapping[str, Any]
    """Additional configuration options for the engine."""

    def __init__(
        self,
        *,
        device: int | None = None,
        memory_resource: Any | None = None,
        raise_on_fail: bool = False,
        monitoring: bool = False,
        **kwargs: Any,
    ) -> None:
        # We do want a named param for `monitoring`, because otherwise it will silently
        # end up in `kwargs`
        if monitoring:
            msg = "query monitoring is not supported by the GPU engine"
            raise NotImplementedError(msg)
        super().__init__(monitoring=False)

        self.device = device
        self.memory_resource = memory_resource
        # Avoids need for changes in cudf-polars
        kwargs["raise_on_fail"] = raise_on_fail
        self.config = kwargs

    def _post_opt_callback(
        self, *, background: bool, eager: bool
    ) -> Callable[[Any, int | None], None] | None:
        if background:
            issue_warning(
                "GPU engine does not support background collection, disabling GPU engine.",
                category=UserWarning,
            )
            return None
        if eager:

View on GitHub (pinned to 68506541d2)

Solutions

1. Run the query on the CPU engine if you need query monitoring; the GPU engine does not support it.

When it happens

Trigger: Thrown at py-polars/src/polars/lazyframe/engine.py:937 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of pola-rs/polars@68506541d2 (2026-08-19). Data as JSON: /api/errors/295fb9f930223c4d. Report an issue: GitHub.