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Description
Bug report
Bug description:
Potential follow up after the merge of #125663 (introduce buffersize param in Executor.map).
"Bug": concurrent.futures.Executor.map temporarily exceeds its buffersize while collecting the next result:
Let's define:
results: Iterator = executor.map(fn, iterable, buffersize=buffersize)What happens when calling next(results):
- fetch the next
argfrominterableand put a task forfn(arg)in the buffer - wait for next result to be available
- yield the collected result
So during step 2. the buffer's size is actually buffersize + 1.
If we want a strict guarantee that there is at most buffersize concurrent tasks even during a next, we have to swap step 1. and step 2.
CPython versions tested on:
CPython main branch
Operating systems tested on:
No response