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https://issues.apache.org/jira/browse/TEZ-2237?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14382911#comment-14382911
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Hitesh Shah commented on TEZ-2237:
----------------------------------
[~cchepelov] Ignore my comment on the catching/ignoring the exception.
{code]
try {
keySerializer.serialize(key);
} catch (BufferTooSmallException e) {
if (metaStart == 0) { // Started writing at the start of the buffer.
Write Key to disk.
// Key too large for any buffer. Write entire record to disk.
currentBuffer.reset();
writeLargeRecord(key, value, partition);
return;
} else { // Exceeded length on current buffer.
// Try resetting the buffer to the next one, if this was not the start
of a buffer,
// and begin spilling the current buffer to disk if it has any records.
setupNextBuffer();
write(key, value, partition);
return;
}
{code}
I am guessing hadoop.TupleSerialization$SerializationElementWriter is hitting
the BTSE and it will fall back based on teh code above. A lot of this has to do
with the fact that the output has a very small buffer. The 215 attempt log
shows 191 spills to disk due to inadequate buffer size. The attempt took around
3 mins to run though.
> 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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