pub fn end_phase()Expand description
Deactivates the arena. New allocations go to the system allocator; existing arena
pointers stay valid until the next begin_phase() resets the slabs.
With the rayon-flush feature (default), this also drains rayon’s internal
queues to release any crossbeam-deque blocks allocated during the phase.
Idempotent: calling end_phase() while no phase is active is a no-op.