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https://issues.apache.org/jira/browse/TEZ-2237?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14382962#comment-14382962
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Rajesh Balamohan commented on TEZ-2237:
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Thanks for sharing the details. From the task log, it appears that the memory
allocated to UnorderedPartitionedKVWriter is very low and it keeps triggering
the BTSE. Can you to set "tez.task.scale.memory.ratios=4, 1, 1, 10, 10, 1, 1"
(4 indicates the ratio allocated for unorderedpartitioned case, default would
be 1).
When BTSE is encountered, tez spills to disk to release memory. It if might be
safe not to log the exception if it is an instance of BTSE (which will help
reducing the size of the task log).
> BufferTooSmallException raised in UnorderedPartitionedKVWriter then DAG
> lingers
> -------------------------------------------------------------------------------
>
> Key: TEZ-2237
> URL: https://issues.apache.org/jira/browse/TEZ-2237
> Project: Apache Tez
> Issue Type: Bug
> Affects Versions: 0.6.0
> Environment: Debian Linux "jessie"
> OpenJDK Runtime Environment (build 1.8.0_40-internal-b27)
> OpenJDK 64-Bit Server VM (build 25.40-b25, mixed mode)
> 7 * Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz, 16/24 GB RAM per node, 1*system
> disk + 4*1 or 2 TiB HDD for HDFS & local (on-prem, dedicated hardware)
> Scalding 0.13.1 modified with https://github.com/twitter/scalding/pull/1220
> to run Cascading 3.0.0-wip-90 with TEZ 0.6.0
> Reporter: Cyrille Chépélov
> Attachments: appmaster____syslog_dag_1427282048097_0215_1.red.txt.gz,
> appmaster____syslog_dag_1427282048097_0237_1.red.txt.gz,
> syslog_attempt_1427282048097_0215_1_21_000014_0.red.txt.gz,
> syslog_attempt_1427282048097_0237_1_70_000028_0.red.txt.gz
>
>
> On a specific DAG with many vertices (actually part of a larger meta-DAG),
> after about a hour of processing, several BufferTooSmallException are raised
> in UnorderedPartitionedKVWriter (about one every two or three spills).
> Once these exceptions are raised, the DAG remains indefinitely "active",
> tying up memory and CPU resources as far as YARN is concerned, while little
> if any actual processing takes place.
> It seems two separate issues are at hand:
> 1. BufferTooSmallException are raised even though, small as the actually
> allocated buffers seem to be (around a couple megabytes were allotted whereas
> 100MiB were requested), the actual keys and values are never bigger than 24
> and 1024 bytes respectively.
> 2. In the event BufferTooSmallExceptions are raised, the DAG fails to stop
> (stop requests appear to be sent 7 hours after the BTSE exceptions are
> raised, but 9 hours after these stop requests, the DAG was still lingering on
> with all containers present tying up memory and CPU allocations)
> The emergence of the BTSE prevent the Cascade to complete, preventing from
> validating the results compared to traditional MR1-based results. The lack of
> conclusion renders the cluster queue unavailable.
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