https://docs.python.org/3/library/multiprocessing.html#multiprocessing.pool.Pool.starmap says:

starmap(func, iterable[, chunksize])
Like map() except that the elements of the iterable are expected to be iterables that are unpacked as arguments.

Hence an iterable of [(1,2), (3, 4)] results in [func(1,2), func(3,4)].



If it was like map() then it would have returned an iterator.  Please clarify, that Pool.map and Pool.starmap return list.

Pool.starmap is not like map from the standard library, as the hyperlinking on the word map() suggests, but like Pool.map().  The latter talks about the chunksize parameter, but the former and Pool.starmap don't.

If the idea is one day to switch the return type to an iterable/generator, returning from starmap() before all parallel executions have completed, this needs to be documented and the typeshed adjusted accordingly.

This appears to have been fixed in PR 26560 in the main branch, but it might be nice to backport it to 3.10 and 3.9

PR 30191 and PR 30192 are backports

pull_requests: + pull_request28412
stage: backport needed -> patch review

pull_requests: + pull_request28411
stage: backport needed -> backport needed

messages: + msg408862

type: enhancement -> behavior
stage: backport needed