Use condition variable in NIOThreadPool #2964
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Motivation: The thread performance checker warns that a threads with QoS are waiting on threads in the NIOThreadPool. We can avoid these warnings by using a condition variable instead. Modifications: - Replace the usage of a semaphore and lock in NIOThreadPool with a condition lock. - The condition value indicates whether the threads have work to do (where work is processing work items or exiting their run loop). Result: Fewer warnings
Lukasa
reviewed
Nov 8, 2024
Sources/NIOPosix/NIOThreadPool.swift
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| case .shuttingDown, .stopped: | ||
| return [] | ||
| return (unlockWith: .hasWork, result: []) |
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Good question. I don't think we need to unlock with a value here, if we're already shutting down then we've already signalled there's work for the threads to do, we don't need to do that again.
glbrntt
commented
Nov 8, 2024
Lukasa
reviewed
Nov 8, 2024
Sources/NIOPosix/NIOThreadPool.swift
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| case .shuttingDown, .stopped: | ||
| return body | ||
| workState = .hasWork |
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Same question here. It might be useful to write out the strategy for the lock value in a comment above it, which will make it easier to audit.
Lukasa
approved these changes
Nov 19, 2024
Lukasa
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to Lukasa/swift-nio
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this pull request
Nov 22, 2024
Motivation: The thread performance checker warns that a threads with QoS are waiting on threads in the NIOThreadPool. We can avoid these warnings by using a condition variable instead. Modifications: - Replace the usage of a semaphore and lock in NIOThreadPool with a condition lock. - The condition value indicates whether the threads have work to do (where work is processing work items or exiting their run loop). Result: - Fewer warnings - Resolves apple#2960 (cherry picked from commit af0e612)
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Motivation:
The thread performance checker warns that a threads with QoS are waiting on threads in the NIOThreadPool. We can avoid these warnings by using a condition variable instead.
Modifications:
Result: