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From els...@apache.org
Subject svn commit: r1575095 - /accumulo/site/trunk/content/release_notes/1.5.1.mdtext
Date Thu, 06 Mar 2014 23:32:43 GMT
Author: elserj
Date: Thu Mar  6 23:32:43 2014
New Revision: 1575095

URL: http://svn.apache.org/r1575095
Log:
ACCUMULO-2394 Add a paragraph about MTBW fixes

Modified:
    accumulo/site/trunk/content/release_notes/1.5.1.mdtext

Modified: accumulo/site/trunk/content/release_notes/1.5.1.mdtext
URL: http://svn.apache.org/viewvc/accumulo/site/trunk/content/release_notes/1.5.1.mdtext?rev=1575095&r1=1575094&r2=1575095&view=diff
==============================================================================
--- accumulo/site/trunk/content/release_notes/1.5.1.mdtext (original)
+++ accumulo/site/trunk/content/release_notes/1.5.1.mdtext Thu Mar  6 23:32:43 2014
@@ -61,6 +61,16 @@ Apache Thrift is used as the internal RP
 users to configure the maximum frame size an Accumulo server will read. This 
 prevents non Accumulo client from connecting and causing memory exhaustion.
 
+### MultiTableBatchWriter concurrency
+
+The MultiTableBatchWriter is a class which allows multiple tables to be written to
+from a single object that maintains a single buffer for caching Mutations across all tables.
This is desirable
+as it greatly simplifies the JVM heap usage from caching Mutations across
+many tables. Sadly, in Apache Accumulo 1.5.0, concurrent access to a single MultiTableBatchWriter
+heavily suffered from synchronization issues. [ACCUMULO-1833][35] introduces a fix
+which alleviates the blocking and idle-wait that previously occurred when multiple threads
accessed
+a single MultiTableBatchWriter instance concurrently.
+
 ### Hadoop Versions
 
 Since Apache Accumulo 1.5.0 was released, Apache Hadoop 2.2.0 was also released
@@ -68,7 +78,7 @@ as the first generally available (GA) Ha
 for a number of reasons, but this also caused additional effort on Accumulo's part to
 ensure that Apache Accumulo continues to work across multiple Hadoop versions. Apache Accumulo
1.5.1
 should function with any recent Hadoop 1 or Hadoop 2 without any special steps, tricks or
instructions
-required. 
+required.
 
 
 ## Notable Bug Fixes
@@ -182,3 +192,4 @@ The following documentation updates were
 [32]: https://issues.apache.org/jira/browse/ACCUMULO-2223
 [33]: https://issues.apache.org/jira/browse/ACCUMULO-2226
 [34]: https://issues.apache.org/jira/browse/ACCUMULO-1470
+[35]: https://issues.apache.org/jira/browse/ACCUMULO-1833



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