# Phase scheduler knobs

**🟡 Intermediate · Lesson 20**

Conjure runs the compile pipeline (phases 1-11) through the PhaseScheduler - a worker pool with a barrier timeout. Two config knobs tune it: workers per spellbook and the barrier timeout. Slow CI boxes raise the timeout; tiny worlds run one worker.

## Before you run

Use the [Intermediate guide](../../intermediate/index.md) for prerequisite concepts. Run from a checkout with Melder installed and Python 3.14 free-threading selected. The collection download includes the level's local helper modules.

## Run the saved script

```bash
python UX_and_AIX_experiences/02_intermediate/20_phase_scheduler_knobs.py
```

```powershell
py -3.14t UX_and_AIX_experiences/02_intermediate/20_phase_scheduler_knobs.py
```

{download}`Download this collection <../../downloads/intermediate-examples.zip>` · [Source on GitHub](https://github.com/Synaptic724/melder/blob/a30a754d0bb61db0b142936010cdb82cffecec6f/UX_and_AIX_experiences/02_intermediate/20_phase_scheduler_knobs.py)

## Public surface

phase_scheduler_workers_per_spellbook,
                   phase_scheduler_barrier_timeout_milliseconds

## Code

```{literalinclude} ../../downloads/02_intermediate/20_phase_scheduler_knobs.py
:language: python
:linenos:
```

## Check the outcome

The script contains its own assertions or demonstrated refusal paths. Run it to evaluate those checks against your installed version. The code above is taken directly from the saved file; no run output is invented here.

[More intermediate examples](index.md) · [Level guide](../../intermediate/index.md)

## Related guides

- [Configuration before conjure](../../intermediate/configuration.md)