cabal-install: add --build-timings flag by sheaf · Pull Request #11769 · haskell/cabal

sheaf · 2026-04-27T17:40:18Z

This new flag makes cabal-install dump timing information for the various stages of building a package. This allows us to better see how much time is spending in configure/build stages.

I used this to figure out where we were wasting time for PRs #11767 and #11768. I think it makes sense to add it as a flag so that all users can get better observability (a bit like the -dshow-passes GHC flag).

Template Α: This PR modifies behaviour or interface

Include the following checklist in your PR:

Patches conform to the coding conventions.
Any changes that could be relevant to users have been recorded in the changelog.
The documentation has been updated, if necessary.
Manual QA notes have been included.
Tests have been added.

TeofilC

This looks great to me!

I am currently working on a tool for nicely visualizing module graph build times. I think I could probably be able to use the same tool for visualizing package graph build times.

If this is accepted, then I might make a followup PR to also output this information to a file in dist-newstyle (along with dependency information) and that should work well with my tool

Mikolaj

Thank you!

ulysses4ever · 2026-04-30T17:50:02Z

Thanks for the PR!

I don't want to drag this longer than necessary, but I can't stand asking: how about a machine-readable version of this? Basically, spitting a CSV might be nice. But again it's more of food-for-thought kind of quetsion rather than an actual concern.

sheaf · 2026-05-04T08:22:28Z

Thanks for the PR!

I don't want to drag this longer than necessary, but I can't stand asking: how about a machine-readable version of this? Basically, spitting a CSV might be nice. But again it's more of food-for-thought kind of quetsion rather than an actual concern.

Yes, that would be nice as well. I think I will let @TeofilC take care of that, given that he has a direct use case for it. I just put up this PR as it's what I was using to benchmark #11768 and #11767 and I thought it might be generally useful.

Mikolaj · 2026-06-18T17:54:29Z

@sheaf: do you think this is ready for merging? If so, could you set a label.

zlonast · 2026-06-27T12:08:26Z

@sheaf may have missed it too

This new flag makes cabal-install dump timing information for the various stages of building a package. This allows us to better see how much time is spending in configure/build stages.

mergify · 2026-06-27T15:08:54Z

Queued — the merge queue status continues in this comment ↓.

mergify · 2026-06-27T15:09:00Z

Merge Queue Status

✅ Entered queue — 2026-06-27 15:08 UTC · Rule: default · triggered by rule Put pull requests in the rebase+merge queue
❌ Checks failed — 2026-06-27 22:31 UTC · on draft merge queue: checking master (d64d329) and [#11787 + #11769] together #12044
✂️ Bisecting to identify the failing PR (round 1/1)
❌ Checks failed · on draft merge queue: checking master (d64d329) and #11769 together #12046 · identified as the failing PR
🚫 Left the queue — 2026-06-27 22:40 UTC · at 68a73d0f2e746e3ba057563e69613bd8672ac8b1

This pull request spent 7 hours 31 minutes 28 seconds in the queue, including 1 hour 53 minutes 11 seconds running CI.

Waiting for

All conditions

Reason

The merge conditions cannot be satisfied due to failing checks

docs/readthedocs.org:cabal
fourmolu
hlint
whitespace
Check sdist post job
Changelogs

Failing checks:

Hint

You may have to fix your CI before adding the pull request to the queue again.
If you update this pull request, to fix the CI, it will automatically be requeued once the queue conditions match again.
If you think this was a flaky issue instead, you can requeue the pull request, without updating it, by posting a @mergifyio queue comment.

zlonast · 2026-06-28T08:57:58Z

@Mergifyio queue

mergify · 2026-06-28T08:58:11Z

Merge Queue Status

✅ Entered queue — 2026-06-28 08:58 UTC · Rule: default · triggered by @zlonast with the @mergifyio queue command
❌ Checks failed — 2026-06-28 09:08 UTC · on draft merge queue: checking master (bc27d17) and [#11787 + #11769] together #12049
✂️ Bisecting to identify the failing PR (round 1/1)
🚫 Left the queue — 2026-06-28 14:29 UTC · at 68a73d0f2e746e3ba057563e69613bd8672ac8b1

This pull request spent 5 hours 31 minutes 36 seconds in the queue, including 3 hours 33 minutes 52 seconds running CI.

Reason

The merge conditions cannot be satisfied due to failing checks

Doctest Cabal
Meta checks
docs/readthedocs.org:cabal
Validate post job
fourmolu
hlint
Bootstrap post job
whitespace
Check sdist post job
Changelogs

Failing checks:

🛑 Create a GitHub LTS prerelease with the binary artifacts (job log)
🛑 Create a GitHub prerelease with the binary artifacts (job log)
🛑 Dogfooding ${{ matrix.sys.os }} ghc-${{ matrix.ghc }} (job log)
❌ Validate macos-latest ghc-9.4.8 (job log)
🛑 Validate old ghcs ${{ matrix.extra-ghc }} (job log)
❌ Validate post job (job log)
🛑 Validate ubuntu-latest ghc-9.10.3 (job log)

Hint

You may have to fix your CI before adding the pull request to the queue again.
If you update this pull request, to fix the CI, it will automatically be requeued once the queue conditions match again.
If you think this was a flaky issue instead, you can requeue the pull request, without updating it, by posting a @mergifyio queue comment.

zlonast · 2026-06-28T14:39:13Z

@Mergifyio queue

mergify · 2026-06-28T14:39:23Z

sheaf force-pushed the build-timings branch 6 times, most recently from e6e0ce1 to 2a9032c Compare April 28, 2026 12:34

sheaf marked this pull request as ready for review April 29, 2026 11:52

sheaf added the attention: needs-review label Apr 29, 2026

This was referenced Apr 30, 2026

Keep a running InstalledPackageIndex to skip expensive per-package ghc-pkg calls #11767

Merged

Configure the compiler ProgramDb once per project #11768

Merged

TeofilC approved these changes Apr 30, 2026

View reviewed changes

Comment thread cabal-install/src/Distribution/Client/ProjectBuilding/UnpackedPackage.hs Outdated

Comment thread cabal-install/src/Distribution/Client/ProjectBuilding/UnpackedPackage.hs Outdated

Mikolaj approved these changes Apr 30, 2026

View reviewed changes

Comment thread changelog.d/build-timings.md

sheaf force-pushed the build-timings branch 2 times, most recently from 85d962c to e4e4801 Compare May 4, 2026 09:19

Mikolaj removed the attention: needs-review label May 14, 2026

sheaf added the merge me Tell Mergify Bot to merge label Jun 18, 2026

mergify Bot added ready and waiting Mergify is waiting out the cooldown period merge delay passed Applied (usually by Mergify) when PR approved and received no updates for 2 days waiting too long automatically set by Mergify to trigger a warning labels Jun 18, 2026

cabal-install: add --build-timings flag

68a73d0

This new flag makes cabal-install dump timing information for the various stages of building a package. This allows us to better see how much time is spending in configure/build stages.

sheaf force-pushed the build-timings branch from e4e4801 to 68a73d0 Compare June 27, 2026 12:44

mergify Bot added the queued label Jun 27, 2026

mergify Bot added a commit that referenced this pull request Jun 27, 2026

Merge of #11769

83a48c6

mergify Bot mentioned this pull request Jun 27, 2026

Add program prefix and suffix to BuildOptions #11787

Merged

5 tasks

mergify Bot mentioned this pull request Jun 27, 2026

merge queue: checking master (ee7d5da), #12017, #12006 and [#11787 + #11769] together #12042

Closed

mergify Bot added a commit that referenced this pull request Jun 27, 2026

Merge of #11769

8189314

mergify Bot mentioned this pull request Jun 27, 2026

merge queue: checking master (d64d329) and [#11787 + #11769] together #12044

Closed

mergify Bot added a commit that referenced this pull request Jun 27, 2026

Merge of #11769

ad3b28e

mergify Bot mentioned this pull request Jun 27, 2026

merge queue: checking master (d64d329) and #11769 together #12046

Closed

84 tasks

mergify Bot added dequeued and removed queued labels Jun 27, 2026

mergify Bot added queued and removed dequeued labels Jun 28, 2026

mergify Bot added a commit that referenced this pull request Jun 28, 2026

Merge of #11769

bc27e5d

mergify Bot mentioned this pull request Jun 28, 2026

merge queue: checking master (bc27d17) and [#11787 + #11769] together #12049

Closed

mergify Bot added dequeued and removed queued labels Jun 28, 2026

mergify Bot added queued and removed dequeued labels Jun 28, 2026

mergify Bot added a commit that referenced this pull request Jun 28, 2026

Merge of #11769

447aaa1

mergify Bot mentioned this pull request Jun 28, 2026

merge queue: checking master (e4d6c7c) and #11769 together #12052

Closed

84 tasks

mergify Bot merged commit d1fc7dc into haskell:master Jun 28, 2026
79 checks passed

mergify Bot removed the queued label Jun 28, 2026

Uh oh!

Conversation

sheaf commented Apr 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

TeofilC left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Mikolaj left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

ulysses4ever commented Apr 30, 2026

Uh oh!

sheaf commented May 4, 2026

Uh oh!

Mikolaj commented Jun 18, 2026

Uh oh!

zlonast commented Jun 27, 2026

Uh oh!

mergify Bot commented Jun 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

mergify Bot commented Jun 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Merge Queue Status

Reason

Hint

Uh oh!

zlonast commented Jun 28, 2026

Uh oh!

mergify Bot commented Jun 28, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Merge Queue Status

Reason

Hint

Uh oh!

zlonast commented Jun 28, 2026

Uh oh!

mergify Bot commented Jun 28, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Merge Queue Status

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

sheaf commented Apr 27, 2026 •

edited

Loading

TeofilC left a comment •

edited

Loading

mergify Bot commented Jun 27, 2026 •

edited

Loading

mergify Bot commented Jun 27, 2026 •

edited

Loading

mergify Bot commented Jun 28, 2026 •

edited

Loading

mergify Bot commented Jun 28, 2026 •

edited

Loading