[ https://issues.apache.org/jira/browse/HBASE-2248?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

stack reassigned HBASE-2248:

Assignee: ryan rawson
Provide new non-copy mechanism to assure atomic reads in get and scan

Key: HBASE-2248
URL: https://issues.apache.org/jira/browse/HBASE-2248
Project: Hadoop HBase
Issue Type: Bug
Affects Versions: 0.20.3
Reporter: Dave Latham
Assignee: ryan rawson
Priority: Blocker
Fix For: 0.20.4

Attachments: HBASE-2248-demonstrate-previous-impl-bugs.patch, HBASE-2248-GetsAsScans3.patch, HBASE-2248-rr-alpha3.txt, HBASE-2248-rr-pre-durability2.txt, HBASE-2248-rr-pre-durability3.txt, hbase-2248.gc, HBASE-2248.patch, hbase-2248.txt, profile.png, put_call_graph.png, readownwrites-lost.2.patch, readownwrites-lost.patch, Screen shot 2010-02-23 at 10.33.38 AM.png, threads.txt

HBASE-2037 introduced a new MemStoreScanner which triggers a ConcurrentSkipListMap.buildFromSorted clone of the memstore and snapshot when starting a scan.
After upgrading to 0.20.3, we noticed a big slowdown in our use of short scans. Some of our data repesent a time series. The data is stored in time series order, MR jobs often insert/update new data at the end of the series, and queries usually have to pick up some or all of the series. These are often scans of 0-100 rows at a time. To load one page, we'll observe about 20 such scans being triggered concurrently, and they take 2 seconds to complete. Doing a thread dump of a region server shows many threads in ConcurrentSkipListMap.biuldFromSorted which traverses the entire map of key values to copy it.
This message is automatically generated by JIRA.
If you think it was sent incorrectly contact one of the administrators: https://issues.apache.org/jira/secure/Administrators.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira

Search Discussions

Related Discussions

Discussion Navigation
viewthread | post
Discussion Overview
groupissues @
categorieshbase, hadoop
postedApr 12, '10 at 6:20p
activeApr 12, '10 at 6:20p

1 user in discussion

stack (JIRA): 1 post



site design / logo © 2018 Grokbase