Rishabh Daim created OAK-12119:
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Summary: Offline Compaction does not persist compacted head into
gc.log
Key: OAK-12119
URL: https://issues.apache.org/jira/browse/OAK-12119
Project: Jackrabbit Oak
Issue Type: Bug
Reporter: Rishabh Daim
Assignee: Rishabh Daim
*Root Cause*
The offline compaction in *Compact.run()* calls *compactFull()* and
*cleanup()* as two separate calls, but the _CompactionResult_ from compaction
is silently discarded between them.
*Call chain:*
Compact.run()
├─ store.compactFull()
│ └─ garbageCollector.compactFull(strategy).isSuccess()
│ ^^^^^^^^^^^
│ CompactionResult.succeeded(...) is returned but thrown away!
│
└─ store.cleanup()
└─ garbageCollector.cleanup(strategy)
└─ strategy.cleanup(context) ← no-arg overload
└─ AbstractGarbageCollectionStrategy.cleanup(Context):
return cleanup(context, CompactionResult.skipped(...))
^^^^^^^^^^^^^^^^^^^^^^^^^^^
Always creates a SKIPPED result!
Why *gc.log* is never written:
In *AbstractGarbageCollectionStrategy.java:88–95:*
// Standalone cleanup always creates a SKIPPED result
{code:java}
public List<String> cleanup(Context context) throws IOException {
return cleanup(context, CompactionResult.skipped(...));
}{code}
*CompactionResult.skipped(...)* inherits *requiresGCJournalEntry()* from the
base class, which returns false (line 216).
Then in *newCleanupStrategyContext()* at line 295–297:
{code:java}
public GCJournal getGCJournal()
{ return compactionResult.requiresGCJournalEntry() ?
context.getGCJournal() : null; // ↑ false for skipped → returns null!
}{code}
*DefaultCleanupStrategy* receives null for gcJournal, so it skips the
gcJournal.persist(...) call entirely.
Contrast with online (integrated) GC:
The *AbstractGarbageCollectionStrategy.run()* method calls *cleanup(context,
compactionResult)* with the actual *CompactionResult.succeeded(...)* — that's
why gc.log works online
but not offline.
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