[jira] [Work started] (HIVE-24297) LLAP buffer collision causes NPE

["Ádám Szita (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-24297?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Work on HIVE-24297 started by Ádám Szita.
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> LLAP buffer collision causes NPE
> --------------------------------
>
>                 Key: HIVE-24297
>                 URL: https://issues.apache.org/jira/browse/HIVE-24297
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Ádám Szita
>            Assignee: Ádám Szita
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> HIVE-23741 introduced an optimization so that CacheTags are not stored on buffer level, but rather on file level, as one cache tag can only relate to one file. With this change a buffer->filecache reference was introduced so that the buffer's tag can be calculated with an extra indirection i.e. buffer.filecache.tag.
> However during buffer collision in putFileData method, we don't set the filecache reference of the collided (new) buffer: [https://github.com/apache/hive/commit/2e18a7408a8dd49beecad8d66bfe054b7dc474da#diff-d2ccd7cf3042845a0812a5e118f82db49253d82fc86449ffa408903bf434fb6dR309-R311]
> Later this cases NPE when the new (instantly decRef'ed) buffer is evicted:
> {code:java}
> Caused by: java.lang.NullPointerException
>         at java.util.concurrent.ConcurrentSkipListMap.doGet(ConcurrentSkipListMap.java:778)
>         at java.util.concurrent.ConcurrentSkipListMap.get(ConcurrentSkipListMap.java:1546)
>         at org.apache.hadoop.hive.llap.cache.CacheContentsTracker.getTagState(CacheContentsTracker.java:129)
>         at org.apache.hadoop.hive.llap.cache.CacheContentsTracker.getTagState(CacheContentsTracker.java:125)
>         at org.apache.hadoop.hive.llap.cache.CacheContentsTracker.reportRemoved(CacheContentsTracker.java:109)
>         at org.apache.hadoop.hive.llap.cache.CacheContentsTracker.notifyEvicted(CacheContentsTracker.java:238)
>         at org.apache.hadoop.hive.llap.cache.LowLevelLrfuCachePolicy.evictSomeBlocks(LowLevelLrfuCachePolicy.java:276)
>         at org.apache.hadoop.hive.llap.cache.CacheContentsTracker.evictSomeBlocks(CacheContentsTracker.java:177)
>         at org.apache.hadoop.hive.llap.cache.LowLevelCacheMemoryManager.reserveMemory(LowLevelCacheMemoryManager.java:98)
>         at org.apache.hadoop.hive.llap.cache.LowLevelCacheMemoryManager.reserveMemory(LowLevelCacheMemoryManager.java:65)
>         at org.apache.hadoop.hive.llap.cache.BuddyAllocator.allocateMultiple(BuddyAllocator.java:323)
>         at org.apache.hadoop.hive.ql.io.orc.encoded.EncodedReaderImpl.allocateMultiple(EncodedReaderImpl.java:1302)
>         at org.apache.hadoop.hive.ql.io.orc.encoded.EncodedReaderImpl.readEncodedStream(EncodedReaderImpl.java:930)
>         at org.apache.hadoop.hive.ql.io.orc.encoded.EncodedReaderImpl.readEncodedColumns(EncodedReaderImpl.java:506)
>         ... 16 more {code}



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