JuliaLang/julia

Consider improving performance of rand! for view of BitArray

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#41,862 opened on Aug 11, 2021

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help wantedperformance

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Description

Currently the fast path for rand! is used only for BitArray but not for views of BitArray:

julia> x = falses(10^8);

julia> y = @view x[:];

julia> @time rand!(x);
  0.002921 seconds

julia> @time rand!(y);
  0.206912 seconds (1 allocation: 48 bytes)

I propose to add support for views also (it requires careful handling of view boundaries along the fastest changing dimension, but for large vectors this should be negligible overhead).

Contributor guide

Research direction
Study the implementation of rand! for BitArray and extend it to support views by handling view boundaries along the fastest changing dimension.
Tech stack
None
Domain
performance
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.
Half day
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
JuliaGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65