Julian Chandra Sutadi created HBASE-30454:
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Summary: BucketCache persistence recovery downgrades MULTI blocks
to SINGLE
Key: HBASE-30454
URL: https://issues.apache.org/jira/browse/HBASE-30454
Project: HBase
Issue Type: Bug
Reporter: Julian Chandra Sutadi
HBASE-29667 reported that blocks written into the BucketCache were initialized
with MULTI priority instead of SINGLE, so the SINGLE to MULTI promotion on
re-access never took effect. The issue was fixed by initializing non-memory
blocks as SINGLE in the BucketEntry constructor.
However, when the cache is restored from its persistence file
(BucketProtoUtils.fromPB), the BucketEntry is rebuilt from its boolean inMemory
instead of the saved priority. The constructor sets MEMORY if inMemory is true
and SINGLE otherwise, so a persisted MULTI block comes back as SINGLE. After a
restart, frequently accessed blocks silently lose their MULTI status and are
more likely to be evicted until they are read again.
{code:java}
// BucketProtoUtils.toPB(BucketEntry): saves all three priorities
.setPriority(toPB(entry.getPriority()))
// BucketProtoUtils.fromPB: reduces the priority to a boolean
new BucketEntry(..., protoValue.getCachedTime(),
protoValue.getPriority() == BucketCacheProtos.BlockPriority.memory, //
inMemory
createRecycler, ByteBuffAllocator.HEAP);
// BucketEntry constructor (fixed by HBASE-29667)
this.priority = inMemory ? BlockPriority.MEMORY : BlockPriority.SINGLE;
{code}
The suggested fix is to restore the enum directly, mirroring the existing
toPB(BlockPriority). We will submit the fix proposal soon.
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