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https://issues.apache.org/jira/browse/HIVE-21686?focusedWorklogId=241300&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-241300
]
ASF GitHub Bot logged work on HIVE-21686:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 13/May/19 20:46
Start Date: 13/May/19 20:46
Worklog Time Spent: 10m
Work Description: odraese commented on pull request #626: [HIVE-21686]
ensure that memory allocator does not evict using brute …
URL: https://github.com/apache/hive/pull/626#discussion_r283523113
##########
File path:
llap-server/src/java/org/apache/hadoop/hive/llap/cache/BuddyAllocator.java
##########
@@ -352,18 +440,21 @@ public void allocateMultiple(MemoryBuffer[] dest, int
size, BufferObjectFactory
LlapIoImpl.LOG.info("Failed to deallocate after a partially
successful allocate: " + dest[i]);
}
}
+ //Need to release the un-allocated but reserved memory.
+ memoryManager.releaseMemory(dest.length - destAllocIx << allocLog2);
String msg = "Failed to allocate " + size + "; at " + destAllocIx +
" out of "
+ dest.length + " (entire cache is fragmented and locked, or an
internal issue)";
logOomErrorMessage(msg);
throw new AllocatorOutOfMemoryException(msg);
}
- ++attempt;
+ ++discardsAttempt;
}
} finally {
+ //@TODO CHECK i think it is a bug, we do not have to release this memory
if we already did deallocate(dest[i])
Review comment:
The deallocate path doesn't increment memoryForceReleased, so this here
should be fine.
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Issue Time Tracking
-------------------
Worklog Id: (was: 241300)
Time Spent: 2h 40m (was: 2.5h)
> Brute Force eviction can lead to a random uncontrolled eviction pattern.
> ------------------------------------------------------------------------
>
> Key: HIVE-21686
> URL: https://issues.apache.org/jira/browse/HIVE-21686
> Project: Hive
> Issue Type: Bug
> Reporter: slim bouguerra
> Assignee: slim bouguerra
> Priority: Major
> Labels: pull-request-available
> Attachments: Cache_hitrate_improvement.csv, HIVE-21686.2.patch,
> HIVE-21686.patch
>
> Time Spent: 2h 40m
> Remaining Estimate: 0h
>
> Current logic used by brute force eviction can lead to a perpetual random
> eviction pattern.
> For instance if the cache build a small pocket of free memory where the total
> size is greater than incoming allocation request, the allocator will randomly
> evict block that fits a particular size.
> This can happen over and over therefore all the eviction will be random.
> In Addition this random eviction will lead a leak in the linked list
> maintained by the policy since it does not know anymore about what is evicted
> and what not.
> The improvement of this patch is very substantial to TPC-DS benchmark. I
> have tested it with 10TB scale 9 llap nodes and 32GB cache size per node.
> The patch has showed very noticeable difference in the Hit rate for raw
> number [^Cache_hitrate_improvement.csv]
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