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Outdated suggestions cannot be applied.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.
concat
produces a lazy sequence, which makes its repeated usage in aloop a potential stack overflow hazard (when the produced seq gets
realized and has to recur over its subseqs).
Background: I've been trying to introduce clojure to a java/kotlin project. Clojure tests kept on dying with a
StackOverflowError
in CI during test discovery, with stacktrace mentioningconcat
. I couldn't debug the issue very well - it wasn't reliably reproducible locally - but noticed that apparently all AOTted classes in test classpath were being scanned for tests, which is a lot of classes. I've run grep onjovial
, found a single use ofconcat
in a loop and tried to replace it with a non-lazy equivalent. Tests run fine with the patched version. I'm not 100% convinced thatconcat
's laziness was the sole culprit due to flakiness of local test runs, but if it helps it helps.