# default_pool()

The process-wide default pool, or None when none is set.

Usage

[Source](https://github.com/shikokuchuo/pymizu/blob/main/python/pymizu/__init__.py#L1455-L1478)

``` python
default_pool()
```

Set with [`set_default_pool()`](../reference/set_default_pool.md#pymizu.set_default_pool); scoped use with [`using_pool()`](../reference/using_pool.md#pymizu.using_pool). Package code taking an optional pool resolves it in this order: an explicit [pool](../reference/Task.pool.md#pymizu.Task.pool) argument, then [`current_pool()`](../reference/current_pool.md#pymizu.current_pool) inside a task (the evaluating worker's own pool, for nested submission), then [default_pool()](../reference/default_pool.md#pymizu.default_pool), then the caller's own fallback -- sequential execution or an error.

Setting a default checks the type only: a stopped pool is accepted (liveness is transient; a probe would prove nothing about use time) and fails at use time with the usual stopped-pool errors. Handles from [`Pool.attach()`](../reference/Pool.attach.md#pymizu.Pool.attach) are valid defaults; ownership and teardown stay with the pool's creator.

The default is process-global -- every thread sees the same pool, and [`current_pool()`](../reference/current_pool.md#pymizu.current_pool) remains the thread-local mechanism. After a `fork()`, a child process reads it as unset: handles are process-private.