Fix flaky test by relying on fake clock#2157
Open
pquentin wants to merge 3 commits into
Open
Conversation
pquentin
added
the
:internal
pquentin
requested review from
gbanasiak and
stevereads-elastic
and removed request for
a team
pquentin
requested review from
a team,
b-deam,
inqueue and
stevereads-elastic
and removed request for
a team,
b-deam,
gbanasiak,
inqueue and
stevereads-elastic
Member
Author
|
Sorry for the multiple review requests; I was testing to check that GitHub respected the "Busy" status. |
Contributor
There was a problem hiding this comment.
Pull request overview
This PR stabilizes a flaky throughput-throttling unit test by replacing real wall-clock timing and actual sleeps with a virtual clock that deterministically advances time and records sleep intervals, making the test fast and CI-robust across slower environments (notably macOS).
Changes:
- Added a
VirtualClockandVirtualRequestTimingtest helper to control time progression and observe sleep behavior. - Updated
test_execute_schedule_throughput_throttledto monkeypatch driver timing/sleep functions and assert deterministic sample counts and throttling behavior.
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
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
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
For a target throughput of 1000 ops/s and 4 clients, we need 250 ops/s per client, which is one operation every ~4ms. On macOS, the CI overhead is large enough that we sometimes only get 107 operations, roughly one every ~9ms. This happened at least twice today:
Instead of relying on wall-clock time and actually sleeping, we can patch the driver's time functions to observe the sleep calls. It's both fast and precise, at the cost of some monkeypatching.