golang/go

time: optimize time.Time.Sub and time.Since

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#17,858 opened on Nov 8, 2016

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Performancehelp wanted

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Description

According to a profiling data from a large number of servers at Google, time.Time.Sub is within the top 150 functions by CPU time. The current implementation of Sub is not inlineable. The logic for Sub is not particularly complicated and I believe it can be made to be inlined with some love.

Contributor guide

Research direction
Study the current implementation of time.Time.Sub in the Go source code, understand why it is not inlineable (e.g., complexity, calls to non inlineable functions), and experiment with refactoring to make it inlineable. Benchmark the optimized version against the original.
Tech stack
go
Domain
backend
Issue type
Performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Gocompiler inlining heuristics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20