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From "Michael Ho (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4026: Implement double-buffering for BlockingQueue
Date Sat, 17 Sep 2016 18:25:27 GMT
Michael Ho has uploaded a new patch set (#4).

Change subject: IMPALA-4026: Implement double-buffering for BlockingQueue
......................................................................

IMPALA-4026: Implement double-buffering for BlockingQueue

With recent changes to improve the parquet scanner's efficency,
row batches are produced more quickly, leading to higher contention
in the blocking queue shared between scanner threads and the scan
node. The contention happens between different producers (i.e.
the scanner threads) and also to a lesser extent, between the
scanner threads and the scan node.

This change addresses the contention between the scanner threads
and the scan node by splitting the queue into a 'read_list_' and
a 'write_list_'. The consumers will consume from 'read_list_' until
it's exhausted while the producers will enqueue into 'write_list_'
until it's full. When 'read_list_' is exhausted, the consumer will
atomically swap the 'read_list_' with 'write_list_'. This reduces
the contention/overhead: 'read_list_' and 'write_list_' are protected
by two different locks so consumer only contends for the
write lock when 'read_list_' is empty.

Change-Id: Ib9f4cf351455efefb0f3bb791cf9bc82d1421d54
---
M be/src/common/compiler-util.h
M be/src/exec/hdfs-scan-node.cc
M be/src/exec/hdfs-scan-node.h
M be/src/util/blocking-queue.h
A be/src/util/condition-variable.h
5 files changed, 184 insertions(+), 61 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/50/4350/4
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Ib9f4cf351455efefb0f3bb791cf9bc82d1421d54
Gerrit-PatchSet: 4
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Michael Ho <kwho@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Chen Huang <paulhuang34@utexas.edu>
Gerrit-Reviewer: Dan Hecht <dhecht@cloudera.com>
Gerrit-Reviewer: Michael Ho <kwho@cloudera.com>
Gerrit-Reviewer: Mostafa Mokhtar <mmokhtar@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>

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