Environment variables

A reference for every environment variable polar_high reads at runtime. All variables are optional — the defaults give zero-overhead behaviour and match what Problem.solve() / Problem.write_mps() do out of the box.

You'd set one of these to:

• Profile / instrument. Print per-phase RSS markers when you are diagnosing a memory hot spot during MPS export or autoscale range detection.
• Opt out of a build optimisation. Fall back to a pre-optimisation code path if you suspect it of a numerical regression.
• Override polars threading.

For runtime tuning on the polar-high side that is not an env var (solver options, release=True), see Performance.

Profiling / instrumentation

All three profiling switches print to stderr only when set; when unset they short-circuit before any psutil call, so the overhead is exactly zero.

Variable	Default	Set to	What it does
POLAR_HIGH_WRITE_MPS_PROFILE	unset (off)	1	Print per-phase and per-constraint-family RSS deltas during Problem.write_mps. Use when an MPS write OOMs or balloons unexpectedly. Also covers Problem.canonicalise — when that runs inside Problem.solve / WarmProblem._initial_build, set this to see per-family checkpoints from the canonical matrix build.
POLAR_HIGH_RANGES_PROFILE	unset (off)	1	Print per-family and per-term RSS during autoscale range detection (autoscale._ranges). Use when range detection on a large LP shows a peak you cannot localise.
POLAR_HIGH_SOLVE_PROFILE	unset (off)	1	Print per-phase RSS markers from Problem.solve (_solve_streaming cold path, ~27 checkpoints) and from WarmProblem._initial_build (~18 checkpoints covering the per-family LP-build loop and the HiGHS handoff). Combine with POLAR_HIGH_WRITE_MPS_PROFILE=1 to also see the per-family canonicalise checkpoints; the two streams interleave by wall time.

Example — diagnose write_mps memory:

POLAR_HIGH_WRITE_MPS_PROFILE=1 python -m my_model.build_and_export 2> mps_profile.log

The output is one line per profiling checkpoint with the current RSS and the delta since the previous checkpoint. Grep for the largest deltas to find the phase that allocated.

Safety / opt-out

Variable	Default	Set to	What it does
POLAR_HIGH_DISABLE_PRUNE_DOWN	unset (off — prune-down active)	1	Disable the per-atomic prune-down for Param chains in _build_canonical_matrix (RHS), _build_lhs_pruned_plan (LHS), _solve_streaming and WarmProblem._initial_build. With the var set, every multi-atomic chain falls through to the original merged-lazy semi-join path. Use as a fallback if a future model surfaces a numerical drift on the prune-down path; report the affected scenario so the engine can be fixed and the env var retired. Numerics are identical between the two paths for all currently-tested scenarios.
POLAR_HIGH_DISABLE_WHERE_PUSHDOWN	unset (off — pushdown active)	1	Disable the pure-filter Where(expr, frame) deferral added in v2.3.0. With the var set, every Where call eagerly inner-joins frame into t.lazy and clears the leaf metadata (var_source, coef_scalar, where_frames) exactly as the pre-v2.3.0 path. Use as a fallback if a model surfaces a numerical drift on the pushdown path; the LP matrix is byte-identical between the two paths for all tested scenarios.

Polars threading

Variable	Default	Set to	What it does
POLARS_MAX_THREADS	1 (set by polar_high at import)	any positive integer	The number of threads polars uses across the whole process. polar_high calls os.environ.setdefault at import time, so setting the variable yourself before importing wins.

This is a polars variable, not a polar_high variable, but polar_high defaults it to 1 for the reasons in Performance — Threading. To override, set it before import polar_high (or before any other module that imports polars). The setdefault no-ops once a value is already present.

See also

• Performance — release=True, solver options, and the underlying build-path reasoning behind the profiling vars above.
• FlexTool documents its own FLEXTOOL_* variables (the env-vars page is still on a not-yet-default branch, so it isn't published at a stable URL yet). FLEXTOOL_SAVE_MEMORY=1 enables a subprocess solver path that benefits from POLAR_HIGH_WRITE_MPS_PROFILE when diagnosing the MPS write step in that path.