morsapaes commented on a change in pull request #352:
URL: https://github.com/apache/flink-web/pull/352#discussion_r449391209
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File path: _posts/2020-06-29-release-1.11.0.md
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@@ -0,0 +1,299 @@
+---
+layout: post
+title: "Apache Flink 1.11.0 Release Announcement"
+date: 2020-06-29T08:00:00.000Z
+categories: news
+authors:
+- morsapaes:
+ name: "Marta Paes"
+ twitter: "morsapaes"
+
+excerpt: The Apache Flink community is proud to announce the release of Flink
1.11.0! This release marks the first milestone in realizing a new vision for
fault tolerance in Flink, and adds a handful of new features that simplify (and
unify) Flink handling across the API stack. In particular for users of the
Table API/SQL, this release introduces significant improvements to usability
and opens up completely new use cases, including the much-anticipated support
for Change Data Capture (CDC)! A great deal of effort has also gone into
optimizing PyFlink and ensuring that its functionality is available to a
broader set of Flink users.
+---
+
+The Apache Flink community is proud to announce the release of Flink 1.11.0!
This release marks the first milestone in realizing a new vision for fault
tolerance in Flink, and adds a handful of new features that simplify (and
unify) Flink handling across the API stack. In particular for users of the
Table API/SQL, this release introduces significant improvements to usability
and opens up completely new use cases, including the much-anticipated support
for Change Data Capture (CDC)! A great deal of effort has also gone into
optimizing PyFlink and ensuring that its functionality is available to a
broader set of Flink users.
+
+This blog post describes all major new features and improvements, important
changes to be aware of and what to expect moving forward.
+
+{% toc %}
+
+The binary distribution and source artifacts are now available on the updated
[Downloads page]({{ site.baseurl }}/downloads.html) of the Flink website, and
the most recent distribution of PyFlink is available on
[PyPI](https://pypi.org/project/apache-flink/). For more details, check the
complete [release
changelog](https://issues.apache.org/jira/secure/ReleaseNote.jspa?version=12346364&styleName=Html&projectId=12315522)
and the [updated documentation]({{ site.DOCS_BASE_URL
}}flink-docs-release-1.11/flink-docs-release-1.11/).
+
+We encourage you to download the release and share your feedback with the
community through the [Flink mailing
lists](https://flink.apache.org/community.html#mailing-lists) or
[JIRA](https://issues.apache.org/jira/projects/FLINK/summary).
+
+## New Features and Improvements
+
+### Unaligned Checkpoints (Beta)
+
+Triggering a checkpoint in Flink will cause a [checkpoint barrier]({{
site.DOCS_BASE_URL
}}flink-docs-release-1.11/internals/stream_checkpointing.html#barriers) to flow
from the sources of your topology all the way towards the sinks. For operators
that receive more than one input stream, the barriers flowing through each
channel need to be aligned before the operator can snapshot its state and
forward the checkpoint barrier — typically, this alignment will take just a few
milliseconds to complete, but it can become a bottleneck in backpressured
pipelines as:
+
+ * Checkpoint barriers will flow much slower through backpressured channels,
effectively blocking the remaining channels and their upstream operators during
checkpointing;
+
+ * Slow checkpoint barrier propagation leads to longer checkpointing times and
can, worst case, result in little to no progress in the application.
+
+To improve the performance of checkpointing under backpressure scenarios, the
community is rolling out the first iteration of unaligned checkpoints
([FLIP-76](https://cwiki.apache.org/confluence/display/FLINK/FLIP-76%3A+Unaligned+Checkpoints))
with Flink 1.11. Compared to the original checkpointing mechanism (Fig. 1),
this approach doesn’t wait for barrier alignment across input channels, instead
allowing barriers to overtake in-flight records and forwarding them downstream
before the synchronous part of the checkpoint takes place (Fig. 2).
+
+<div style="line-height:60%;">
+ <br>
+</div>
+
+<div class="row">
+ <div class="col-lg-6">
+ <div class="text-center">
+ <figure>
+ <img src="{{ site.baseurl
}}/img/blog/2020-06-29-release-1.11.0/image1.gif" width="600px" alt="Aligned
Checkpoints"/>
+ <br/><br/>
+ <figcaption><i><b>Fig.1:</b> Aligned
Checkpoints</i></figcaption>
+ </figure>
+ </div>
+ </div>
+ <div class="col-lg-6">
+ <div class="text-center">
+ <figure>
+ <img src="{{ site.baseurl
}}/img/blog/2020-06-29-release-1.11.0/image2.png" width="600px" alt="Unaligned
Checkpoints"/>
+ <br/><br/>
+ <figcaption><i><b>Fig.2:</b> Unaligned
Checkpoints</i></figcaption>
+ </figure>
+ </div>
+ </div>
+</div>
+
+<div style="line-height:150%;">
+ <br>
+</div>
+
+Because in-flight records have to be persisted as part of the snapshot,
unaligned checkpoints will lead to increased checkpoints sizes. On the upside,
**checkpointing times are heavily reduced**, so users will see more progress
(even in unstable environments) as more up-to-date checkpoints will lighten the
recovery process. You can learn more about the current limitations of unaligned
checkpoints in the [documentation]({{ site.DOCS_BASE_URL
}}flink-docs-release-1.11/concepts/stateful-stream-processing.html#unaligned-checkpointing),
and track the improvement work planned for this feature in
[FLINK-14551](https://issues.apache.org/jira/browse/FLINK-14551).
Review comment:
I'm updating the link to the limitations to a section of the docs that
is short and clear about it, including the issue with savepoints.
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