7% of the overall runtime spent in SelectableEventLoop.debugDescription
#754
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performance
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Lukasa
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Sep 23, 2024
…Handler (#772) ### Motivation: A performance test executing 100,000 sequential requests against a simple [`NIOHTTP1Server`](https://github.com/apple/swift-nio/blob/main/Sources/NIOHTTP1Server/README.md) revealed that 7% of total run time is spent in the setter of the `request` property in `HTTP1ClientChannelHandler` (GitHub Issue #754). The poor performance comes from [processing the string interpolation `"\(self.eventLoop)"`](https://github.com/swift-server/async-http-client/blob/6df8e1c17e68f0f93de2443b8c8cafca9ddcc89a/Sources/AsyncHTTPClient/ConnectionPool/HTTP1/HTTP1ClientChannelHandler.swift#L39C17-L39C75) which under the hood calls a computed property. This problem can entirely be avoided by storing `eventLoop.description` when initializing `HTTP1ClientChannelHandler`, and using that stored value in `request`'s setter, rather than computing the property each time. ### Modifications: - Created a new property `let eventLoopDescription: Logger.MetadataValue` in `HTTP1ClientChannelHandler` that stores the description of the `eventLoop` argument that is passed into the initializer. - Replaced the string interpolation `"\(self.eventLoop)"` in `request`'s setter with `self.eventLoopDescription`. ### Result: `HTTP1ClientChannelHandler.eventLoop`'s `description` property is cached upon initialization rather than being computed each time in the `request` property's setter. --------- Co-authored-by: Cory Benfield <[email protected]>
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Just noticed that when just running loads of sequential super basic HTTP requests against a fast server (
NIOHTTP1Server), we spent about 7% of the overall runtime inHTTP1ClientChannelHandler.request.setterwhich spends most of its time in_print_unlocked<A, B>(_:_:)because it's pulling adebugDescriptionfor EventLoop for the logger metadata :P (release mode compile of course)Should be an easy fix.
async-http-client/Sources/AsyncHTTPClient/ConnectionPool/HTTP1/HTTP1ClientChannelHandler.swift
Line 39 in 54d1006
FWIW, the super basic perf test I used is this: weissi@bf7dbeb (this code isn't meant to be merged).
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