micro-editor / micro-editor/micro

PgUp/PgDown scrolling slow in large files with softwrap enabled

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#3,964 7 comments 0 reactions 0 assignees View on GitHub

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Dominant language
Go
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Avg merge
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Merged PRs (30d)
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Description

If you open a large-ish file micro will have no problem scrolling line-by line (holding arrow down).
But when you use PgUp/PgDown to scroll a full screen-height, it takes over a second per page.

Example file: https://download.geonames.org/export/dump/cities15000.zip after extraction, which is only 33k lines and 7MB.

It feels like the page scroll is O(n) in file-size, maybe it tries to figure out all line-endings first.

Version: 2.0.14
Commit hash: 5b6eed51f8dff5a9fa00e581d4277e198231fedd

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce with the extracted cities15000 file described in the issue, with softwrap enabled, and compare line-by-line scrolling with PgUp/PgDown. Profile the Go code while paging through the 33k-line, 7MB file to find the file-size-dependent work. Done means page scrolling is responsive at this size without regressing softwrapped navigation.

Written by the indexing model from the issue text.

Assessment

Tech stack
go
Domain
cli, performance
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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