pingcap/tidb

use hack.Slice in ColumnInfo:Dump to avoid unnecessary `string to slice` conversation

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#32,073 opened on Jan 30, 2022

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 (3 comments) (1 reaction) (1 assignee)Go (40,090 stars) (6,186 forks)batch import
help wantedtype/enhancementtype/performance

Description

Enhancement

In some read-heavy workloads, we found that Column Dump causes some CPUs

image

Through the flamegraph, we can see that nearly 1% of CPU is caused by string to slice conversation. We can ensure that we don't change the slice value in the Dump function, https://github.com/pingcap/tidb/blob/master/server/column.go#L41, so we can use hack.Slice instead.

Contributor guide

Tech stack
go
Domain
backendperformance
Issue type
performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Go programming
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
Implement the change in server/column.go line 41 by replacing the string to slice conversion with hack.Slice from the hack package. Ensure that the slice is not modified in the Dump function. Consider checking if there are any other places with similar conversions that could benefit from this optimization. The issue has an assignee, so coordinate with them before submitting a PR.