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From "Prasanth Jayachandran (JIRA)" <>
Subject [jira] [Commented] (HIVE-16180) LLAP: Native memory leak in EncodedReader
Date Sat, 11 Mar 2017 01:08:04 GMT


Prasanth Jayachandran commented on HIVE-16180:

Yes. Orc side changes for ZCR might also be required. I haven't looked into it yet. Will do
in a follow up. 

> LLAP: Native memory leak in EncodedReader
> -----------------------------------------
>                 Key: HIVE-16180
>                 URL:
>             Project: Hive
>          Issue Type: Bug
>          Components: llap
>    Affects Versions: 2.2.0
>            Reporter: Prasanth Jayachandran
>            Assignee: Prasanth Jayachandran
>            Priority: Critical
>         Attachments:, FullGC-15GB-cleanup.png, Full-gc-native-mem-cleanup.png,
HIVE-16180.1.patch, Native-mem-spike.png
> Observed this in internal test run. There is a native memory leak in Orc EncodedReaderImpl
that can cause YARN pmem monitor to kill the container running the daemon. Direct byte buffers
are null'ed out which is not guaranteed to be cleaned until next Full GC. To show this issue,
attaching a small test program that allocates 3x256MB direct byte buffers. First buffer is
null'ed out but still native memory is used. Second buffer user Cleaner to clean up native
allocation. Third buffer is also null'ed but this time invoking a System.gc() which cleans
up all native memory. Output from the test program is below
> {code}
> Allocating 3x256MB direct memory..
> Native memory used: 786432000
> Native memory used after data1=null: 786432000
> Native memory used after data2.clean(): 524288000
> Native memory used after data3=null: 524288000
> Native memory used without gc: 524288000
> Native memory used after gc: 0
> {code}
> Longer term improvements/solutions:
> 1) Use DirectBufferPool from hadoop or netty's
as direct byte buffer allocations are expensive (System.gc() + 100ms thread sleep).
> 2) Use HADOOP-12760 for proper cleaner invocation in JDK8 and JDK9

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