parallel.race

Module nu.core.flows.parallel.race.

Race: first-to-complete fan-in over the async loop.

Async-only: real cancellation of the losers needs a loop. The sync thunk raises as a backstop, but sync run refuses the async-only subtree first.

Race

Runs its children concurrently; first to finish wins - the & composition.

Race(*children)

Path nu.core.flows.Race. Kind Strategy, sort strategy, cardinality void. Arity None (0 required).

Arguments

Yields

Nothing (VOID). The writes are whichever child wins.

Notes

• The losers are cancelled once the first child completes.
• Async-only: _compile raises RuntimeError, and sync run refuses the subtree up front via requires_async.

Example

import asyncio
fast = nu.SetCmd(nu.AttrRef("winner"), "fast")
slow = nu.DelayedDo(1, nu.SetCmd(nu.AttrRef("winner"), "slow"))
asyncio.run(nu.arun(nu.Race(fast, slow)))[1].attrs

Attributes(winner='fast')