[BOOKKEEPER-685] Race in compaction algorithm from BOOKKEEPER-664

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Fix Version/s: 4.2.2
• Assignee: Ivan Kelly
• Reporter: Ivan Kelly
• Created: 13/Sep/13 19:15
• Updated: 02/Oct/13 09:53
• Resolved: 02/Oct/13 09:53

Description

I discovered a race in the algorithm when I was forward porting to trunk.

1) Thread1: flushed.set(false)
2) Thread2: onRotateEntryLog() // flushed.set(true)
3) Thread1: entryLogger addEntry L123-E456
4) Thread1: offsets > max, waits for flushed, flushed is true(as set in 2), L123-E456 updated in ledger cache
5) T2: L123 flushed out of ledger cache
6) Crash

This will possible lose 1 entry. I've only reasoned this, not observed it, but it can happen.

The fix is pretty easy. EntryLoggerListener should notify with the point offset in the entry log it has synced as far as.