Author: elserj
Date: Mon Feb 16 20:05:50 2015
New Revision: 1660193
URL: http://svn.apache.org/r1660193
Log:
Stub out 1.6.2 release notes.
Modified:
accumulo/site/trunk/content/release_notes/1.6.2.mdtext
Modified: accumulo/site/trunk/content/release_notes/1.6.2.mdtext
URL:
http://svn.apache.org/viewvc/accumulo/site/trunk/content/release_notes/1.6.2.mdtext?rev=1660193&r1=1660192&r2=1660193&view=diff
==============================================================================
--- accumulo/site/trunk/content/release_notes/1.6.2.mdtext (original)
+++ accumulo/site/trunk/content/release_notes/1.6.2.mdtext Mon Feb 16 20:05:50
2015
@@ -16,14 +16,16 @@ Notice: Licensed to the Apache Softwa
specific language governing permissions and limitations
under the License.
-Apache Accumulo 1.6.1 is a maintenance release on the 1.6 version branch.
-This release contains changes from over 175 issues, comprised of bug-fixes,
performance
-improvements and better test cases. As this is a maintenance release, Apache
Accumulo
-1.6.1 has no client API incompatibilities over Apache Accumulo 1.6.0. Users
of 1.6.0
-are strongly encouraged to update as soon as possible to benefit from the
improvements.
-
-New users are encouraged to use this release over 1.6.0 or any other older
releases. For
-information about improvements since Accumulo 1.5, see the [1.6.0 release
notes][32].
+Apache Accumulo 1.6.2 is a maintenance release on the 1.6 version branch.
+This release contains changes from over 150 issues, comprised of bug-fixes,
performance
+improvements and better test cases. Apache Accumulo 1.6.2 is the first release
since the
+community has adopted [Semantic Versioning][1] which means that all changes to
the [public API][2]
+are guaranteed to be made without adding to or removing from the public API.
This ensures
+that client code that runs against 1.6.1 is guaranteed to run against 1.6.2
and vice versa.
+
+Users of 1.6.0 or 1.6.1 are strongly encouraged to update as soon as possible
to benefit from
+the improvements with very little concern in change of underlying
functionality. For
+information about improvements since Accumulo 1.5, see the [1.6.0][3] and
[1.6.1][4] release notes.
## Performance Improvements
@@ -31,134 +33,24 @@ Apache Accumulo 1.6.1 includes a number
Many of these improvements were also included in the recently released Apache
Accumulo 1.5.2.
-### Write-Ahead Log sync performance
-
-The Write-Ahead Log (WAL) files are used to ensure durability of updates made
to Accumulo.
-A sync is called on the file in HDFS to make sure that the changes to the WAL
are persisted
-to disk, which allows Accumulo to recover in the case of failure.
[ACCUMULO-2766][9] fixed
-an issue where an operation against a WAL would unnecessarily wait for
multiple syncs, slowing
-down the ingest on the system.
-
-### Minor-Compactions not aggressive enough
-
-On a system with ample memory provided to Accumulo, long hold-times were
observed which
-blocks the ingest of new updates. Trying to free more server-side memory by
running minor
-compactions more frequently increased the overall throughput on the node.
These changes
-were made in [ACCUMULO-2905][10].
-
-### HeapIterator optimization
-
-Iterators, a notable feature of Accumulo, are provided to users as a
server-side programming
-construct, but are also used internally for numerous server operations. One of
these system iterator
-is the HeapIterator which implements a PriorityQueue of other Iterators. One
way this iterator is
-used is to merge multiple files in HDFS to present a single, sorted stream of
Key-Value pairs. [ACCUMULO-2827][11]
-introduces a performance optimization to the HeapIterator which can improve
the speed of the
-HeapIterator in common cases.
-
-### Write-Ahead log sync implementation
-
-In Hadoop-2, two implementations of sync are provided: hflush and hsync. Both
of these
-methods provide a way to request that the datanodes write the data to the
underlying
-medium and not just hold it in memory (the *fsync* syscall). While both of
these methods
-inform the Datanodes to sync the relevant block(s), *hflush* does not wait for
acknowledgement
-from the Datanodes that the sync finished, where *hsync* does. To provide the
most reliable system
-"out of the box", Accumulo defaults to *hsync* so that your data is as secure
as possible in
-a variety of situations (notably, unexpected power outages).
-
-The downside is that performance tends to suffer because waiting for a sync to
disk is a very
-expensive operation. [ACCUMULO-2842][12] introduces a new system property,
tserver.wal.sync.method,
-that lets users to change the HDFS sync implementation from *hsync* to
*hflush*. Using *hflush* instead
-of *hsync* may result in about a 30% increase in ingest performance.
+### Improvement 1
-For users upgrading from Hadoop-1 or Hadoop-0.20 releases, *hflush* is the
equivalent of how
-sync was implemented in these older versions of Hadoop and should give
comparable performance.
+### Improvement 2
## Other improvements
-### Use of Hadoop CredentialProviders
-
-Apache Hadoop 2.6.0 introduced a new API aimed at providing ways to separate
sensitive values
-from being stored in plaintext as a part of [HADOOP-10607][28]. Accumulo has
had two sensitive
-configuration properties stored in *accumulo-site.xml* for every standard
installation: instance.secret
-and trace.token.property.password. If either of these properties are
compromised, it could lead to
-unwanted access of Accumulo. [ACCUMULO-2464][29] modifies Accumulo so that it
can stored any sensitive
-configuration properties in a Hadoop CredentialProvider. With sensitive values
removed from accumulo-site.xml,
-it can be shared without concern and security can be focused solely on the
CredentialProvider.
+### Improvement 1
## Notable Bug Fixes
-### Add configurable maximum frame size to Thrift proxy
-
-The Thrift proxy server was subject to memory exhaustion, typically
-due to bad input, where the server would attempt to allocate a very large
-buffer and die in the process. [ACCUMULO-2658][2] introduces a configuration
-parameter, like [ACCUMULO-2360][3], to prevent this error.
-
-### Offline tables can prevent tablet balancing
-
-Before 1.6.1, when a table with many tablets was created, ingested into, and
-taken offline, tablet balancing may have stoppped. This would happen if there
-were tablet migrations for the table, because the migrations couldn't occur.
-The balancer will not run when there are outstanding migrations; therefore, a
-system could become unbalanced. [ACCUMULO-2694][4] introduces a fix to ensure
-that offline tables do not block balancing and improves the server-side
-logging.
-
-### MiniAccumuloCluster process management
-
-MiniAccumuloCluster had a few issues which could cause deadlock or a method
that
-never returns. Most of these are related to management of the Accumulo
processes
-([ACCUMULO-2764][5], [ACCUMULO-2985][6], and [ACCUMULO-3055][7]).
-
-### IteratorSettings not correctly serialized in RangeInputSplit
-
-The Writable interface methods on the RangeInputSplit class accidentally
omitted
-calls to serialize the IteratorSettings configured for the Job.
[ACCUMULO-2962][8]
-fixes the serialization and adds some additional tests.
-
-### Constraint violation causes hung scans
-
-A failed bulk import transaction had the ability to create an infinitely
retrying
-loop due to a constraint violation. This directly prevents scans from
completing,
-but will also hang compactions. [ACCUMULO-3096][14] fixes the issue so that the
-constraint no longer hangs the entire system.
-
-### Unable to upgrade cleanly from 1.5
-
-When upgrading a table from 1.5.1 to 1.6.0, a user experienced an error where
the table
-never came online. [ACCUMULO-2974][27] fixes an issue from the change of file
references
-stored as absolute paths instead of relative paths in the Accumulo metadata
table.
-
-### Guava dependency changed
-
-[ACCUMULO-3100][30] lowered the dependency on Guava from 15.0 to 14.0.1. This
dependency
-now matches what Hadoop is depending on for the 2.x.y version line. Depending
on a newer
-version of Guava introduces many issues stemming from deprecated classes in
use by Hadoop
-which have been removed. While installations of Accumulo will likely work as
expected with
-newer versions of Guava on the classpath (because the Hadoop processes will
have their own
-classpath), use of MiniDfsClusters with the new Guava version will result in
errors.
-
-Users can attempt to use a newer version of Guava on the Accumulo server
classpath; however,
-the success is dependent on Hadoop client libraries not using (missing) Guava
methods internally.
-
-### Scanners eat InterruptedException
+### Bug fix 1
-Scanners previously consumed InterruptedExceptions and did not exit after. In
multi-threaded
-environments, this is very problematic as there is no means to stop the
Scanner from reading data.
-[ACCUMULO-3030][31] fixes the Scanner so that interrupts are observed and the
Scanner exits as expected.
+### Bug fix 2
## Documentation
The following documentation updates were made:
- * [ACCUMULO-2767][15]
- * [ACCUMULO-2796][16]
- * [ACCUMULO-2919][17]
- * [ACCUMULO-3008][18]
- * [ACCUMULO-2874][19]
- * [ACCUMULO-2821][20]
- * [ACCUMULO-3097][21]
- * [ACCUMULO-3097][22]
## Testing
@@ -176,48 +68,24 @@ and, in HDFS High-Availability instances
</tr>
<tr>
<td>Gentoo</tdt>
- <td>Apache 2.6.0-SNAPSHOT</td>
- <td>2</td>
- <td>Apache 3.4.5</td>
+ <td>N/A</td>
+ <td>1</td>
+ <td>N/A</td>
<td>No</td>
- <td>Unit and Functional Tests, ContinuousIngest w/ verification (2B
entries)</td>
+ <td>Unit and Integration Tests</td>
</tr>
<tr>
<td>CentOS 6</td>
- <td>Apache 2.3.0</td>
+ <td>Keith TBD</td>
<td>20</td>
- <td>Apache 3.4.5</td>
+ <td>Keith TBD</td>
<td>No</td>
- <td>24/hr RandomWalk, ContinuousIngest w/ verification w/ and w/o
agitation (17B entries), 24hr Randomwalk test</td>
+ <td>(Keith Verify this) ContinuousIngest w/ verification w/ and w/o
agitation (31B and 21B entries, respectively)</td>
</tr>
</table>
-[1]: https://issues.apache.org/jira/browse/ACCUMULO-2586
-[2]: https://issues.apache.org/jira/browse/ACCUMULO-2658
-[3]: https://issues.apache.org/jira/browse/ACCUMULO-2360
-[4]: https://issues.apache.org/jira/browse/ACCUMULO-2694
-[5]: https://issues.apache.org/jira/browse/ACCUMULO-2764
-[6]: https://issues.apache.org/jira/browse/ACCUMULO-2985
-[7]: https://issues.apache.org/jira/browse/ACCUMULO-3055
-[8]: https://issues.apache.org/jira/browse/ACCUMULO-2962
-[9]: https://issues.apache.org/jira/browse/ACCUMULO-2766
-[10]: https://issues.apache.org/jira/browse/ACCUMULO-2905
-[11]: https://issues.apache.org/jira/browse/ACCUMULO-2827
-[12]: https://issues.apache.org/jira/browse/ACCUMULO-2842
-[13]: https://issues.apache.org/jira/browse/ACCUMULO-3018
-[14]: https://issues.apache.org/jira/browse/ACCUMULO-3096
-[15]: https://issues.apache.org/jira/browse/ACCUMULO-2767
-[16]: https://issues.apache.org/jira/browse/ACCUMULO-2796
-[17]: https://issues.apache.org/jira/browse/ACCUMULO-2919
-[18]: https://issues.apache.org/jira/browse/ACCUMULO-3008
-[19]: https://issues.apache.org/jira/browse/ACCUMULO-2874
-[20]: https://issues.apache.org/jira/browse/ACCUMULO-2821
-[21]: https://issues.apache.org/jira/browse/ACCUMULO-3097
-[22]: https://issues.apache.org/jira/browse/ACCUMULO-3097
-[27]: https://issues.apache.org/jira/browse/ACCUMULO-2974
-[28]: https://issues.apache.org/jira/browse/HADOOP-10607
-[29]: https://issues.apache.org/jira/browse/ACCUMULO-2464
-[30]: https://issues.apache.org/jira/browse/ACCUMULO-3100
-[31]: https://issues.apache.org/jira/browse/ACCUMULO-3030
-[32]: /release_notes/1.6.0.html
\ No newline at end of file
+[1]: http://semver.org
+[2]: https://github.com/apache/accumulo#api
+[3]: http://accumulo.apache.org/release_notes/1.6.0.html
+[4]: http://accumulo.apache.org/release_notes/1.6.1.html
\ No newline at end of file
