* S3: delay empty folder cleanup to prevent Spark write failures (#8963)
Empty folders were being cleaned up within seconds, causing Apache Spark
(s3a) writes to fail when temporary directories like _temporary/0/task_xxx/
were briefly empty.
- Increase default cleanup delay from 5s to 2 minutes
- Only process queue items that have individually aged past the delay
(previously the entire queue was drained once any item triggered)
- Make the delay configurable via filer.toml:
[filer.options]
s3.empty_folder_cleanup_delay = "2m"
* test: increase cleanup wait timeout to match 2m delay
The empty folder cleanup delay was increased to 2 minutes, so the
Spark integration test needs to wait longer for temporary directories
to disappear.
* fix: eagerly clean parent directories after empty folder deletion
After deleting an empty folder, immediately try to clean its parent
rather than relying on cascading metadata events that each re-enter
the 2-minute delay queue. This prevents multi-minute waits when
cleaning nested temporary directory trees (e.g. Spark's _temporary
hierarchy with 3+ levels would take 6m+ vs near-instant).
Fixes the CI failure where lingering _temporary parent directories
were not cleaned within the test's 3-minute timeout.
a4753b6a3b