Janardhan Hungund created HBASE-28900:
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Summary: Avoid resetting bucket cache during restart if
inconsistency is observed for some blocks.
Key: HBASE-28900
URL: https://issues.apache.org/jira/browse/HBASE-28900
Project: HBase
Issue Type: Bug
Components: BucketCache
Reporter: Janardhan Hungund
During the execution of persistence of backing map into the persistence file,
the backing map is not guarded by a lock against caching of blocks and block
evictions.
Hence, some of the block entries in the backing map in persistence may not be
consistent with the bucket cache.
During, the retrieval of the backing map from persistence if an inconsistency
is detected, the complete bucket cache is discarded and is rebuilt.
One of the errors, seen, is, as mentioned below:
{code:java}
2024-09-30 08:58:33,840 WARN
org.apache.hadoop.hbase.io.hfile.bucket.BucketCache: Can't restore from
file[/hadoopfs/ephfs1/bucketcache.map]. The bucket cache will be reset and
rebuilt. Exception seen:
org.apache.hadoop.hbase.io.hfile.bucket.BucketAllocatorException: Couldn't find
match for index 26 in free list
at
org.apache.hadoop.hbase.io.hfile.bucket.BucketAllocator$Bucket.addAllocation(BucketAllocator.java:140)
at
org.apache.hadoop.hbase.io.hfile.bucket.BucketAllocator.<init>(BucketAllocator.java:406)
at
org.apache.hadoop.hbase.io.hfile.bucket.BucketCache.retrieveFromFile(BucketCache.java:1486)
at
org.apache.hadoop.hbase.io.hfile.bucket.BucketCache.lambda$startPersistenceRetriever$0(BucketCache.java:377)
at java.base/java.lang.Thread.run(Thread.java:840) {code}
This retrieval can be optimised to only discard the inconsistent entries in the
persistent backing map and retain the remaining entries. The bucket cache
validator will throw away the inconsistent entry from the backing map.
Thanks,
Janardhan
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