Fix kqueue timer duration calculation#16581
Merged
ysbaddaden merged 2 commits intocrystal-lang:masterfrom Jan 19, 2026
Merged
Conversation
The timer duration was calculated incorrectly in commit 5bf7b19, causing all timers to fire immediately instead of waiting. The bug was: ```crystal t = Crystal::System::Time.instant.duration_since(time) # = (now - future).clamp(0) = 0 when time is in the future ``` Fixed to: ```crystal t = time.duration_since(Crystal::System::Time.instant) # = (future - now).clamp(0) = remaining time until timer fires ``` This caused 100% CPU usage on macOS as the event loop would spin instead of blocking on kqueue. Added regression test to verify sleep actually takes time. Fixes crystal-lang#16578
Contributor
Author
|
@ysbaddaden do you mind to look and approve? |
Contributor
|
We need 1.19.1 ASAP |
ysbaddaden
reviewed
Jan 19, 2026
Co-authored-by: Johannes Müller <straightshoota@gmail.com>
ysbaddaden
approved these changes
Jan 19, 2026
Collaborator
|
Reproduced on FreeBSD. The issue is fixed 👍 |
straight-shoota
approved these changes
Jan 19, 2026
ysbaddaden
pushed a commit
that referenced
this pull request
Jan 20, 2026
The timer duration was calculated incorrectly in commit 5bf7b19, causing all timers to fire immediately instead of waiting. This caused 100% CPU usage on macOS as the event loop would spin instead of blocking on kqueue. Added regression test to verify sleep actually takes time. Co-authored-by: Sergey Kuznetsov <sergey@iterudit.com>
Collaborator
|
Git push to origin failed for release/1.19 with exitcode 128 |
ysbaddaden
pushed a commit
to ysbaddaden/crystal
that referenced
this pull request
Jan 20, 2026
The timer duration was calculated incorrectly in commit 5bf7b19, causing all timers to fire immediately instead of waiting. This caused 100% CPU usage on macOS as the event loop would spin instead of blocking on kqueue. Added regression test to verify sleep actually takes time. Co-authored-by: Sergey Kuznetsov <sergey@iterudit.com>
ysbaddaden
pushed a commit
that referenced
this pull request
Jan 20, 2026
The timer duration was calculated incorrectly in commit 5bf7b19, causing all timers to fire immediately instead of waiting. This caused 100% CPU usage on macOS as the event loop would spin instead of blocking on kqueue. Added regression test to verify sleep actually takes time. Co-authored-by: Sergey Kuznetsov <sergey@iterudit.com>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
6 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Fix
The timer duration was calculated incorrectly in commit 5bf7b19 (#16498), causing all timers to fire immediately instead of waiting.
Bug:
Fix:
Impact
This caused 100% CPU usage on macOS as the event loop would spin instead of blocking on kqueue. Every Crystal application on macOS is affected.
Testing
Added regression test to verify
sleepactually takes time.Fixes #16578