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From els...@apache.org
Subject [1/4] accumulo git commit: Minor updates to 1.7.2 release notes.
Date Thu, 23 Jun 2016 15:02:05 GMT
Repository: accumulo
Updated Branches:
  refs/heads/asf-site b1bf6c22e -> 45d81dfc4
  refs/heads/gh-pages a9b0fda04 -> 6538290f3


Minor updates to 1.7.2 release notes.


Project: http://git-wip-us.apache.org/repos/asf/accumulo/repo
Commit: http://git-wip-us.apache.org/repos/asf/accumulo/commit/6538290f
Tree: http://git-wip-us.apache.org/repos/asf/accumulo/tree/6538290f
Diff: http://git-wip-us.apache.org/repos/asf/accumulo/diff/6538290f

Branch: refs/heads/gh-pages
Commit: 6538290f370ab48ad59526c87b5733c60a31cafa
Parents: a9b0fda
Author: Josh Elser <elserj@apache.org>
Authored: Thu Jun 23 10:55:04 2016 -0400
Committer: Josh Elser <elserj@apache.org>
Committed: Thu Jun 23 10:55:04 2016 -0400

----------------------------------------------------------------------
 release_notes/1.7.2.md | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/accumulo/blob/6538290f/release_notes/1.7.2.md
----------------------------------------------------------------------
diff --git a/release_notes/1.7.2.md b/release_notes/1.7.2.md
index 5ffce6f..eebdc70 100644
--- a/release_notes/1.7.2.md
+++ b/release_notes/1.7.2.md
@@ -31,6 +31,10 @@ There was a bug ([ACCUMULO-4148][ACCUMULO-4148]) where multiple put calls
with i
 
 An improvement was introduced to allow a max age before WAL files would be automatically
rolled. Without a max age, they could stay open for writing indefinitely, blocking the Hadoop
DataNode decomissioning process. For more information, see [ACCUMULO-4004][ACCUMULO-4004].
 
+### Remove copy of cached RFile index blocks
+
+Accumulo maintains an cache for file blocks in-memory as a performance optimization. This
can be done safely because Accumulo RFiles are immutable, thus their blocks are also immutable.
There are two types of these blocks: index and data blocks. Index blocks refer to the b-tree
style index inside of each Accumulo RFile, while data blocks contain the sorted Key-Value
pairs. In previous versions, when Accumulo extracted an Index block from the in-memory cache,
it would copy the data. [ACCUMULO-4164][ACCUMULO-4164] removes this unnecessary copy as the
contents are immutable and can be passed by reference. Ensuring that the Index blocks are
not copied when accessed from the cache is a big performance gain at the file-access level.
+
 ### Minor performance improvements.
 
 Tablet servers would previously always hsync at the start of a minor compaction, causing
delays in the write pipeline. These additional syncs were determined to provide no additional
durability guarantees and have been removed. See [ACCUMULO-4112][ACCUMULO-4112] for additional
detail.
@@ -40,13 +44,13 @@ A performance issue was identified and corrected ([ACCUMULO-1755][ACCUMULO-1755]
 
 ## Other Notable Changes
 
- * [ACCUMULO-4146][ACCUMULO-4146] Avoid copy of RFile Index Blocks when already in cache.
- * [ACCUMULO-4335][ACCUMULO-4335] Error conditions that result in a Halt should ensure non-zero
process exit code.
- * [ACCUMULO-4334][ACCUMULO-4334] Ingest rates reported through JMX did not match rates reported
by Monitor.
- * [ACCUMULO-4314][ACCUMULO-4314] Use statistics to choose better keys for RFile index.
  * [ACCUMULO-3923][ACCUMULO-3923] bootstrap_hdfs.sh script would copy incorrect jars to hdfs.
+ * [ACCUMULO-4146][ACCUMULO-4146] Avoid copy of RFile Index Blocks when already in cache.
  * [ACCUMULO-4155][ACCUMULO-4155] No longer publish javadoc for non-public API to website.
(Still available in javadoc jars in maven)
  * [ACCUMULO-4173][ACCUMULO-4173] Provide balancer to balance table within subset of hosts.
+ * [ACCUMULO-4314][ACCUMULO-4314] Use statistics to choose better keys for RFile index.
+ * [ACCUMULO-4334][ACCUMULO-4334] Ingest rates reported through JMX did not match rates reported
by Monitor.
+ * [ACCUMULO-4335][ACCUMULO-4335] Error conditions that result in a Halt should ensure non-zero
process exit code.
 
 ## Testing
 
@@ -78,3 +82,4 @@ HDFS High-Availability instances, forcing NameNode failover.
 [ACCUMULO-4155]: https://issues.apache.org/jira/browse/ACCUMULO-4155
 [ACCUMULO-4173]: https://issues.apache.org/jira/browse/ACCUMULO-4173
 [ACCUMULO-4151]: https://issues.apache.org/jira/browse/ACCUMULO-4151
+[ACCUMULO-4164]: https://issues.apache.org/jira/browse/ACCUMULO-4164


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