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https://issues.apache.org/jira/browse/HBASE-29857?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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rstest updated HBASE-29857:
---------------------------
Description:
When a RegionServer with BucketCache persistence enabled is restarted, if the
BucketCache was empty at shutdown time, the new RegionServer fails to start
with a `NullPointerException` in `BucketCache.parsePB()`.
The bug is in the interaction between `BucketProtoUtils.serializeAsPB()` and
`BucketCache.retrieveChunkedBackingMap()`:
1. **During shutdown with empty cache**: When `backingMap.size() == 0`,
`serializeAsPB()` writes `numChunks = 0` to the persistence file, but the loop
that writes `BucketCacheEntry` objects never executes (because there are no
entries to iterate). This means **no BucketCacheEntry is written to the file**.
2. **During startup**: `retrieveChunkedBackingMap()` reads `numChunks = 0` from
the file, but still attempts to read the first chunk using
`parseDelimitedFrom()`. Since no `BucketCacheEntry` was written,
`parseDelimitedFrom()` returns `null`.
3. **NPE occurs**: The null `firstChunk` is passed to `parsePB()`, which calls
`firstChunk.getDeserializersMap()` on the null object, causing NPE.
Use the attached test can reproduce this bug.
was:
When a RegionServer with BucketCache persistence enabled is restarted, if the
BucketCache was empty at shutdown time, the new RegionServer fails to start
with a `NullPointerException` in `BucketCache.parsePB()`.
> BucketCache fails to start when persistence file was written with empty cache
> -----------------------------------------------------------------------------
>
> Key: HBASE-29857
> URL: https://issues.apache.org/jira/browse/HBASE-29857
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Affects Versions: 2.6.3
> Reporter: rstest
> Priority: Major
>
> When a RegionServer with BucketCache persistence enabled is restarted, if the
> BucketCache was empty at shutdown time, the new RegionServer fails to start
> with a `NullPointerException` in `BucketCache.parsePB()`.
>
> The bug is in the interaction between `BucketProtoUtils.serializeAsPB()` and
> `BucketCache.retrieveChunkedBackingMap()`:
> 1. **During shutdown with empty cache**: When `backingMap.size() == 0`,
> `serializeAsPB()` writes `numChunks = 0` to the persistence file, but the
> loop that writes `BucketCacheEntry` objects never executes (because there are
> no entries to iterate). This means **no BucketCacheEntry is written to the
> file**.
> 2. **During startup**: `retrieveChunkedBackingMap()` reads `numChunks = 0`
> from the file, but still attempts to read the first chunk using
> `parseDelimitedFrom()`. Since no `BucketCacheEntry` was written,
> `parseDelimitedFrom()` returns `null`.
> 3. **NPE occurs**: The null `firstChunk` is passed to `parsePB()`, which
> calls `firstChunk.getDeserializersMap()` on the null object, causing NPE.
> Use the attached test can reproduce this bug.
>
>
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