[HIVE-24444] compactor.Cleaner should not set state "mark cleaned" if there are obsolete files in the FS

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Labels: pull-request-available
• Assignee: Karen Coppage
• Reporter: Karen Coppage
• Created: 30/Nov/20 09:02
• Updated: 04/Dec/20 10:40
• Resolved: 04/Dec/20 10:40

Description

This is an improvement on HIVE-24314, in which markCleaned() is called only if any files are deleted by the cleaner. This could cause a problem in the following case:

Say for table_1 compaction1 cleaning was blocked by an open txn, and compaction is run again on the same table (compaction2). Both compaction1 and compaction2 could be in "ready for cleaning" at the same time. By this time the blocking open txn could be committed. When the cleaner runs, one of compaction1 and compaction2 will remain in the "ready for cleaning" state:
Say compaction2 is picked up by the cleaner first. The Cleaner deletes all obsolete files. Then compaction1 is picked up by the cleaner; the cleaner doesn't remove any files and compaction1 will stay in the queue in a "ready for cleaning" state.

HIVE-24291 already solves this issue but if it isn't usable (for example if HMS schema changes are out the question) then HIVE-24314 + this change will fix the issue of the Cleaner not removing all obsolete files.

Issue Links

• links to: GitHub Pull Request #1716