pola-rs/polars · error

POLARS_MEMORY_PREFETCH=madvise_sequential is not supported b

Error message

POLARS_MEMORY_PREFETCH=madvise_sequential is not supported by this system

What it means

Panic while parsing POLARS_MEMORY_PREFETCH: the value 'madvise_sequential' was requested, but the posix madvise(MADV_SEQUENTIAL) path is cfg'd to unix-only and this build/run is on a non-unix target. The prefetch strategy cannot be applied, so memory-prefetch initialization aborts.

Source

Thrown at crates/polars-utils/src/mem.rs:125

                #[cfg(target_family = "unix")]
                {
                    madvise_willneed
                }
                #[cfg(not(target_family = "unix"))]
                {
                    no_prefetch
                }
            },
            Some("no_prefetch") => no_prefetch,
            Some("prefetch_l2") => prefetch_l2,
            Some("madvise_sequential") => {
                #[cfg(target_family = "unix")]
                {
                    madvise_sequential
                }
                #[cfg(not(target_family = "unix"))]
                {
                    panic!(
                        "POLARS_MEMORY_PREFETCH=madvise_sequential is not supported by this system"
                    );
                }
            },
            Some("madvise_willneed") => {
                #[cfg(target_family = "unix")]
                {
                    madvise_willneed
                }
                #[cfg(not(target_family = "unix"))]
                {
                    panic!(
                        "POLARS_MEMORY_PREFETCH=madvise_willneed is not supported by this system"
                    );
                }
            },
            Some("madvise_populate_read") => {
                #[cfg(target_os = "linux")]

View on GitHub (pinned to 9b5d73fd00)

Solutions

  1. madvise_sequential is unsupported on this OS; unset POLARS_MEMORY_PREFETCH or choose another mode.

Example fix

unset POLARS_MEMORY_PREFETCH
Defensive patterns

Strategy: fallback

When it happens

Trigger: POLARS_MEMORY_PREFETCH=madvise_sequential on a platform without that madvise flag.

Common situations: See trigger scenarios.

AI-assisted analysis of pola-rs/polars@9b5d73fd00 (2026-08-19). Data as JSON: /api/errors/c404e050e94c7f88. Report an issue: GitHub.