default_pool()

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

Usage

Source

default_pool()

Set with set_default_pool(); scoped use with using_pool(). Package code taking an optional pool resolves it in this order: an explicit pool argument, then current_pool() inside a task (the evaluating worker’s own pool, for nested submission), then 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() 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() remains the thread-local mechanism. After a fork(), a child process reads it as unset: handles are process-private.