microsoft/Terminal

[Performance] Replace std::vector with more lightweight structure in `RenderData::GetPatternId`

Open

#10,564 opened on Jul 6, 2021

View on GitHub
 (8 comments) (1 reaction) (0 assignees)C++ (3,212 forks)batch import
Area-PerformanceArea-RenderingHelp WantedIssue-TaskProduct-Meta

Repository metrics

Stars
 (35,764 stars)
PR merge metrics
 (Avg merge 27d 19h) (24 merged PRs in 30d)

Description

This is about the scrolling test in #10563. A simplified repro would be:

time bash -c 'yes | head -n1000000'

which takes 7-8s with windows terminal and 300ms with gnome terminal.

Test case provided by @lhecker.

These lines show up in the hot paths of the trace of OpenConsole:

https://github.com/microsoft/terminal/blob/main/src/renderer/base/renderer.cpp#L788

image

It appears that simply constructing empty std::vector (empty because this is in conhost/OpenConsole) is quite expensive.

CC @PankajBhojwani

Contributor guide

Research direction
Inspect the code at src/renderer/base/renderer.cpp at line 788 in the OpenConsole project. Understand why constructing an empty std::vector is expensive in the hot path. Consider replacing it with a lightweight structure like a fixed size array or a custom small buffer optimization. Profile to verify improvement.
Tech stack
cpp
Domain
desktop
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.
1-3 hours
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.
Mostly clear
Prerequisites
C++STL containers
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40