[lldb] Make MainLoopTest::CallbackWithTimeout slightly more resilient… #11586
+1
−1
Conversation
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
…llvm#162197) Compute the start time *before* registering the callback, rather than after, to avoid the possibility of a small race. The following scenario illustrates the problem. 1. The callback is registered with a 2 second timeout at t=0ms. 2. We compute the start time after registering the callback. For the sake of argument, let's say it took 5ms to return from registering the callback and computing the current time. Start=5ms. 3. The callback fires after exactly 2 seconds, or t=2000ms. 4. We compute the difference between start and now. If it took less than 5ms to compute, then we end up with a difference that's less than 2000ms and the test fails. Let's say it took 3ms this time, then 2003ms-5ms=1998ms < 2000ms. The actual values in the example above are arbitrary. All that matters is that it took longer to compute the start time than the end time. My theory is that this explains why this test is flaky when running under ASan in CI (which has unpredictable timing). rdar://160956999 (cherry picked from commit 605e2d1)
|
@swift-ci test |
|
@swift-ci test macos |
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Outdated suggestions cannot be applied.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.
… (llvm#162197)
Compute the start time before registering the callback, rather than after, to avoid the possibility of a small race.
The following scenario illustrates the problem.
The actual values in the example above are arbitrary. All that matters is that it took longer to compute the start time than the end time. My theory is that this explains why this test is flaky when running under ASan in CI (which has unpredictable timing).
rdar://160956999
(cherry picked from commit 605e2d1)