[ https://issues.apache.org/jira/browse/HBASE-2468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12873079#action_12873079 ]
HBase Review Board commented on HBASE-2468: ------------------------------------------- Message from: "Benoit Sigoure" <tsuna...@gmail.com> ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: http://review.hbase.org/r/78/#review91 ----------------------------------------------------------- src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment515> Remove the spurious spaces around the parenthesis. src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment516> No space before `[]' on this line and the previous line. src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment517> Move the declaration of this variable to line 675 where it's initialized. src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment518> I'm not sure I understand this comment but it could be because I'm not very familiar with this part of the code. src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment519> Do this instead: if (value == null) { return true; // don't cache it } final String serverAddress = Bytes.toString(value); src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment520> I don't understand the last part of the comment ("fetch ahead number of rows in META"). src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment521> No space before `[]'. src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment522> Wrap the `else' on the previous line. src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment523> Instead of doing `+ e.getMessage()', pass `e' in second argument. src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment524> No space before `[]'. src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java <http://review.hbase.org/r/78/#comment525> Remove the second part of the check (tableLogs.values() == null). This can't happen. If it happens, there's a bug in SoftValueSortedMap and we shouldn't hide it. src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java <http://review.hbase.org/r/78/#comment526> No space before `[]'. - Benoit > Improvements to prewarm META cache on clients > --------------------------------------------- > > Key: HBASE-2468 > URL: https://issues.apache.org/jira/browse/HBASE-2468 > Project: HBase > Issue Type: Improvement > Components: client > Reporter: Todd Lipcon > Assignee: Mingjie Lai > Fix For: 0.21.0 > > Attachments: HBASE-2468-trunk.patch > > > A couple different use cases cause storms of reads to META during startup. > For example, a large MR job will cause each map task to hit meta since it > starts with an empty cache. > A couple possible improvements have been proposed: > - MR jobs could ship a copy of META for the table in the DistributedCache > - Clients could prewarm cache by doing a large scan of all the meta for the > table instead of random reads for each miss > - Each miss could fetch ahead some number of rows in META -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.