replace the lock in `exec::__nest_rcvr::__complete` with a CAS loop
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Description
async_scope::spawn is much slower than start_detached, and I suspect the issue is the locking and unlocking going on in exec::__next_rcvr::__complete. There is similar logic for walking a linked list and notifying each element in the implementation of split, but there it is done more efficiently with a compare-and-swap loop. Maybe the two can share logic.
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Research direction
Start with async_scope::spawn and start_detached, then inspect the linked-list notification logic in split. Locate the locking and unlocking in exec::__next_rcvr::__complete (or the __nest_rcvr::__complete named in the title) and compare it with split’s compare-and-swap loop. Done means the completion path uses the CAS-based approach without changing notification behavior or async_scope correctness.
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Assessment
- Tech stack
- cpp
- Domain
- performance
- Issue type
- Refactor
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 38/100