[jira] [Commented] (FLINK-8191) Add a RoundRobinPartitioner to be shipped with the Kafka connector

2018-03-01 Thread Tzu-Li (Gordon) Tai (JIRA) 

[ 
https://issues.apache.org/jira/browse/FLINK-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16383268#comment-16383268
 ] 

Tzu-Li (Gordon) Tai commented on FLINK-8191:


Yes, moving to 1.6.0.

> Add a RoundRobinPartitioner to be shipped with the Kafka connector
> --
>
> Key: FLINK-8191
> URL: https://issues.apache.org/jira/browse/FLINK-8191
> Project: Flink
>  Issue Type: New Feature
>  Components: Kafka Connector
>Reporter: Tzu-Li (Gordon) Tai
>Assignee: Aegeaner
>Priority: Blocker
> Fix For: 1.6.0
>
>
> We should perhaps consider adding a round-robin partitioner ready for use to 
> be shipped with the Kafka connector, along side the already available 
> {{FlinkFixedPartitioner}}.
> See the original discussion here:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/FlinkKafkaProducerXX-td16951.html



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[jira] [Commented] (FLINK-8191) Add a RoundRobinPartitioner to be shipped with the Kafka connector

2018-03-01 Thread Aljoscha Krettek (JIRA) 

[ 
https://issues.apache.org/jira/browse/FLINK-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16382134#comment-16382134
 ] 

Aljoscha Krettek commented on FLINK-8191:
-

[~tzulitai] Did we decide to move this to 1.6.0? Or at least make it 
non-blocking?

> Add a RoundRobinPartitioner to be shipped with the Kafka connector
> --
>
> Key: FLINK-8191
> URL: https://issues.apache.org/jira/browse/FLINK-8191
> Project: Flink
>  Issue Type: New Feature
>  Components: Kafka Connector
>Reporter: Tzu-Li (Gordon) Tai
>Assignee: Aegeaner
>Priority: Blocker
> Fix For: 1.5.0
>
>
> We should perhaps consider adding a round-robin partitioner ready for use to 
> be shipped with the Kafka connector, along side the already available 
> {{FlinkFixedPartitioner}}.
> See the original discussion here:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/FlinkKafkaProducerXX-td16951.html



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[jira] [Commented] (FLINK-8191) Add a RoundRobinPartitioner to be shipped with the Kafka connector

2017-12-11 Thread ASF GitHub Bot (JIRA) 

[ 
https://issues.apache.org/jira/browse/FLINK-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16286777#comment-16286777
 ] 

ASF GitHub Bot commented on FLINK-8191:
---

Github user tzulitai commented on a diff in the pull request:

https://github.com/apache/flink/pull/5116#discussion_r156233639
  
--- Diff: 
flink-connectors/flink-connector-kafka-base/src/test/java/org/apache/flink/streaming/connectors/kafka/FlinkRoundRobinPartitionerTest.java
 ---
@@ -0,0 +1,118 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.streaming.connectors.kafka;
+
+import 
org.apache.flink.streaming.connectors.kafka.partitioner.FlinkRoundRobinPartitioner;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Tests for the {@link FlinkRoundRobinPartitioner}.
+ */
+public class FlinkRoundRobinPartitionerTest {
+   /**
+* Test for when there are more sinks than partitions.
+* 
+*  Flink Sinks:Kafka Partitions
+*  1   >   1
+*  2   --/
+*  3   -/
+*  4   /
+* 
+*/
+   @Test
+   public void testMoreFlinkThanPartitions() {
+   FlinkRoundRobinPartitioner part = new 
FlinkRoundRobinPartitioner<>();
+
+   int[] partitions = new int[]{0};
+
+   part.open(0, 4);
+   Assert.assertEquals(0, part.partition("abc1", null, null, null, 
partitions));
+
+   part.open(1, 4);
+   Assert.assertEquals(0, part.partition("abc2", null, null, null, 
partitions));
+
+   part.open(2, 4);
+   Assert.assertEquals(0, part.partition("abc3", null, null, null, 
partitions));
+   Assert.assertEquals(0, part.partition("abc3", null, null, null, 
partitions)); // check if it is changing ;)
+
+   part.open(3, 4);
+   Assert.assertEquals(0, part.partition("abc4", null, null, null, 
partitions));
+   }
+
+   /**
+* Tests for when there are more partitions than sinks.
+* 
+*  Flink Sinks:Kafka Partitions
+*  1   >   1
+*  2   >   2
+*  
3
+*  
4
+*  
5
+*
+* 
+*/
+   @Test
+   public void testFewerFlinkThanPartitions() {
+   FlinkRoundRobinPartitioner part = new 
FlinkRoundRobinPartitioner<>();
+
+   int[] partitions = new int[]{0, 1, 2, 3, 4};
+   part.open(0, 2);
+   Assert.assertEquals(0, part.partition("abc1", null, null, null, 
partitions));
+   Assert.assertEquals(1, part.partition("abc1", null, null, null, 
partitions));
+   Assert.assertEquals(2, part.partition("abc1", null, null, null, 
partitions));
+   Assert.assertEquals(3, part.partition("abc1", null, null, null, 
partitions));
+   Assert.assertEquals(4, part.partition("abc1", null, null, null, 
partitions));
+
+   part.open(1, 2);
+   Assert.assertEquals(1, part.partition("abc1", null, null, null, 
partitions));
+   Assert.assertEquals(2, part.partition("abc1", null, null, null, 
partitions));
+   Assert.assertEquals(3, part.partition("abc1", null, null, null, 
partitions));
+   Assert.assertEquals(4, part.partition("abc1", null, null, null, 
partitions));
+   Assert.assertEquals(0, part.partition("abc1", null, null, null, 
partitions));
+   }
+
+   /*
+*  Flink Sinks:Kafka Partitions
+*

[jira] [Commented] (FLINK-8191) Add a RoundRobinPartitioner to be shipped with the Kafka connector

2017-12-11 Thread ASF GitHub Bot (JIRA) 

[ 
https://issues.apache.org/jira/browse/FLINK-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16286775#comment-16286775
 ] 

ASF GitHub Bot commented on FLINK-8191:
---

Github user tzulitai commented on a diff in the pull request:

https://github.com/apache/flink/pull/5116#discussion_r156234010
  
--- Diff: 
flink-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/connectors/kafka/partitioner/FlinkRoundRobinPartitioner.java
 ---
@@ -0,0 +1,72 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.streaming.connectors.kafka.partitioner;
+
+import org.apache.flink.util.Preconditions;
+
+/**
+ * A partitioner ensuring that each internal Flink partition communicate 
with Kafka partition in round robin manner.
+ *
+ * Note, one Kafka partition can contain multiple Flink partitions.
+ *
+ * Cases:
+ * # More Flink partitions than kafka partitions
+ * 
+ * Flink Sinks:Kafka Partitions
+ * 1   1
+ * 2   --/
+ * 3   -/
+ * 4   /
+ * 
+ * Some (or all) kafka partitions contain the output of more than one 
flink partition
+ *
+ * Fewer Flink partitions than Kafka
+ * 
+ * Flink Sinks:Kafka Partitions
+ * 1   1
+ * 2   2
+ * 
3
+ * 
4
+ * 
5
+ * 
+ *
+ * All Kafka partitions contain data
+ * This is a round-robin kafka partitioner (note that this will
+ * cause a lot of network connections between all the Flink instances and 
all the Kafka brokers).
+ */
+public class FlinkRoundRobinPartitioner extends 
FlinkKafkaPartitioner {
--- End diff --

Can we rename this to `FlinkRoundRobinPartitioner`?
Its quite a mouthful, but would be more coherent with the naming of 
original partitioners.


> Add a RoundRobinPartitioner to be shipped with the Kafka connector
> --
>
> Key: FLINK-8191
> URL: https://issues.apache.org/jira/browse/FLINK-8191
> Project: Flink
>  Issue Type: New Feature
>  Components: Kafka Connector
>Reporter: Tzu-Li (Gordon) Tai
>Assignee: Aegeaner
>Priority: Blocker
> Fix For: 1.5.0
>
>
> We should perhaps consider adding a round-robin partitioner ready for use to 
> be shipped with the Kafka connector, along side the already available 
> {{FlinkFixedPartitioner}}.
> See the original discussion here:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/FlinkKafkaProducerXX-td16951.html



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[jira] [Commented] (FLINK-8191) Add a RoundRobinPartitioner to be shipped with the Kafka connector

2017-12-11 Thread ASF GitHub Bot (JIRA) 

[ 
https://issues.apache.org/jira/browse/FLINK-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16286776#comment-16286776
 ] 

ASF GitHub Bot commented on FLINK-8191:
---

Github user tzulitai commented on a diff in the pull request:

https://github.com/apache/flink/pull/5116#discussion_r156233400
  
--- Diff: 
flink-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/connectors/kafka/partitioner/FlinkRoundRobinPartitioner.java
 ---
@@ -0,0 +1,72 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.streaming.connectors.kafka.partitioner;
+
+import org.apache.flink.util.Preconditions;
+
+/**
+ * A partitioner ensuring that each internal Flink partition communicate 
with Kafka partition in round robin manner.
+ *
+ * Note, one Kafka partition can contain multiple Flink partitions.
+ *
+ * Cases:
+ * # More Flink partitions than kafka partitions
+ * 
+ * Flink Sinks:Kafka Partitions
+ * 1   1
+ * 2   --/
+ * 3   -/
+ * 4   /
+ * 
+ * Some (or all) kafka partitions contain the output of more than one 
flink partition
+ *
+ * Fewer Flink partitions than Kafka
+ * 
+ * Flink Sinks:Kafka Partitions
+ * 1   1
+ * 2   2
+ * 
3
+ * 
4
+ * 
5
+ * 
+ *
+ * All Kafka partitions contain data
+ * This is a round-robin kafka partitioner (note that this will
+ * cause a lot of network connections between all the Flink instances and 
all the Kafka brokers).
+ */
+public class FlinkRoundRobinPartitioner extends 
FlinkKafkaPartitioner {
+   private int parallelInstanceId;
--- End diff --

nit: can we have an empty line before the class fields? Just a matter of 
taste :)


> Add a RoundRobinPartitioner to be shipped with the Kafka connector
> --
>
> Key: FLINK-8191
> URL: https://issues.apache.org/jira/browse/FLINK-8191
> Project: Flink
>  Issue Type: New Feature
>  Components: Kafka Connector
>Reporter: Tzu-Li (Gordon) Tai
>Assignee: Aegeaner
>Priority: Blocker
> Fix For: 1.5.0
>
>
> We should perhaps consider adding a round-robin partitioner ready for use to 
> be shipped with the Kafka connector, along side the already available 
> {{FlinkFixedPartitioner}}.
> See the original discussion here:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/FlinkKafkaProducerXX-td16951.html



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[jira] [Commented] (FLINK-8191) Add a RoundRobinPartitioner to be shipped with the Kafka connector

2017-12-11 Thread ASF GitHub Bot (JIRA) 

[ 
https://issues.apache.org/jira/browse/FLINK-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16286774#comment-16286774
 ] 

ASF GitHub Bot commented on FLINK-8191:
---

Github user tzulitai commented on a diff in the pull request:

https://github.com/apache/flink/pull/5116#discussion_r156233704
  
--- Diff: 
flink-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/connectors/kafka/partitioner/FlinkRoundRobinPartitioner.java
 ---
@@ -0,0 +1,72 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.streaming.connectors.kafka.partitioner;
+
+import org.apache.flink.util.Preconditions;
+
+/**
+ * A partitioner ensuring that each internal Flink partition communicate 
with Kafka partition in round robin manner.
+ *
+ * Note, one Kafka partition can contain multiple Flink partitions.
+ *
+ * Cases:
+ * # More Flink partitions than kafka partitions
+ * 
+ * Flink Sinks:Kafka Partitions
+ * 1   1
+ * 2   --/
+ * 3   -/
+ * 4   /
+ * 
+ * Some (or all) kafka partitions contain the output of more than one 
flink partition
+ *
+ * Fewer Flink partitions than Kafka
+ * 
+ * Flink Sinks:Kafka Partitions
+ * 1   1
+ * 2   2
+ * 
3
+ * 
4
+ * 
5
+ * 
+ *
+ * All Kafka partitions contain data
--- End diff --

Missing "." period at end of line.


> Add a RoundRobinPartitioner to be shipped with the Kafka connector
> --
>
> Key: FLINK-8191
> URL: https://issues.apache.org/jira/browse/FLINK-8191
> Project: Flink
>  Issue Type: New Feature
>  Components: Kafka Connector
>Reporter: Tzu-Li (Gordon) Tai
>Assignee: Aegeaner
>Priority: Blocker
> Fix For: 1.5.0
>
>
> We should perhaps consider adding a round-robin partitioner ready for use to 
> be shipped with the Kafka connector, along side the already available 
> {{FlinkFixedPartitioner}}.
> See the original discussion here:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/FlinkKafkaProducerXX-td16951.html



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[jira] [Commented] (FLINK-8191) Add a RoundRobinPartitioner to be shipped with the Kafka connector

2017-12-11 Thread ASF GitHub Bot (JIRA) 

[ 
https://issues.apache.org/jira/browse/FLINK-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16286778#comment-16286778
 ] 

ASF GitHub Bot commented on FLINK-8191:
---

Github user tzulitai commented on a diff in the pull request:

https://github.com/apache/flink/pull/5116#discussion_r156233349
  
--- Diff: 
flink-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/connectors/kafka/partitioner/FlinkRoundRobinPartitioner.java
 ---
@@ -0,0 +1,72 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.streaming.connectors.kafka.partitioner;
+
+import org.apache.flink.util.Preconditions;
+
+/**
+ * A partitioner ensuring that each internal Flink partition communicate 
with Kafka partition in round robin manner.
+ *
+ * Note, one Kafka partition can contain multiple Flink partitions.
+ *
+ * Cases:
+ * # More Flink partitions than kafka partitions
+ * 
+ * Flink Sinks:Kafka Partitions
+ * 1   1
+ * 2   --/
+ * 3   -/
+ * 4   /
+ * 
+ * Some (or all) kafka partitions contain the output of more than one 
flink partition
+ *
+ * Fewer Flink partitions than Kafka
+ * 
+ * Flink Sinks:Kafka Partitions
+ * 1   1
+ * 2   2
+ * 
3
+ * 
4
+ * 
5
+ * 
+ *
+ * All Kafka partitions contain data
+ * This is a round-robin kafka partitioner (note that this will
+ * cause a lot of network connections between all the Flink instances and 
all the Kafka brokers).
+ */
+public class FlinkRoundRobinPartitioner extends 
FlinkKafkaPartitioner {
--- End diff --

Annotate this as `@Public`.
I know that the other classes do not have proper usage annotation, but we 
should start doing it for new classes / APIs that we add to the connector.


> Add a RoundRobinPartitioner to be shipped with the Kafka connector
> --
>
> Key: FLINK-8191
> URL: https://issues.apache.org/jira/browse/FLINK-8191
> Project: Flink
>  Issue Type: New Feature
>  Components: Kafka Connector
>Reporter: Tzu-Li (Gordon) Tai
>Assignee: Aegeaner
>Priority: Blocker
> Fix For: 1.5.0
>
>
> We should perhaps consider adding a round-robin partitioner ready for use to 
> be shipped with the Kafka connector, along side the already available 
> {{FlinkFixedPartitioner}}.
> See the original discussion here:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/FlinkKafkaProducerXX-td16951.html



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[jira] [Commented] (FLINK-8191) Add a RoundRobinPartitioner to be shipped with the Kafka connector

2017-12-11 Thread ASF GitHub Bot (JIRA) 

[ 
https://issues.apache.org/jira/browse/FLINK-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16286779#comment-16286779
 ] 

ASF GitHub Bot commented on FLINK-8191:
---

Github user tzulitai commented on a diff in the pull request:

https://github.com/apache/flink/pull/5116#discussion_r156233850
  
--- Diff: 
flink-connectors/flink-connector-kafka-base/src/main/java/org/apache/flink/streaming/connectors/kafka/partitioner/FlinkRoundRobinPartitioner.java
 ---
@@ -0,0 +1,72 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.streaming.connectors.kafka.partitioner;
+
+import org.apache.flink.util.Preconditions;
+
+/**
+ * A partitioner ensuring that each internal Flink partition communicate 
with Kafka partition in round robin manner.
+ *
+ * Note, one Kafka partition can contain multiple Flink partitions.
+ *
+ * Cases:
+ * # More Flink partitions than kafka partitions
+ * 
+ * Flink Sinks:Kafka Partitions
+ * 1   1
+ * 2   --/
+ * 3   -/
+ * 4   /
+ * 
+ * Some (or all) kafka partitions contain the output of more than one 
flink partition
+ *
+ * Fewer Flink partitions than Kafka
+ * 
+ * Flink Sinks:Kafka Partitions
+ * 1   1
+ * 2   2
+ * 
3
+ * 
4
+ * 
5
+ * 
--- End diff --

The above illustrations do not convey the fact that this is a 
`RoundRobinPartitioner`.
For example, the exact same illustrations can also work for the 
`FlinkFixedPartitioner`.


> Add a RoundRobinPartitioner to be shipped with the Kafka connector
> --
>
> Key: FLINK-8191
> URL: https://issues.apache.org/jira/browse/FLINK-8191
> Project: Flink
>  Issue Type: New Feature
>  Components: Kafka Connector
>Reporter: Tzu-Li (Gordon) Tai
>Assignee: Aegeaner
>Priority: Blocker
> Fix For: 1.5.0
>
>
> We should perhaps consider adding a round-robin partitioner ready for use to 
> be shipped with the Kafka connector, along side the already available 
> {{FlinkFixedPartitioner}}.
> See the original discussion here:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/FlinkKafkaProducerXX-td16951.html



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[jira] [Commented] (FLINK-8191) Add a RoundRobinPartitioner to be shipped with the Kafka connector

2017-12-04 Thread ASF GitHub Bot (JIRA) 

[ 
https://issues.apache.org/jira/browse/FLINK-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=16276612#comment-16276612
 ] 

ASF GitHub Bot commented on FLINK-8191:
---

GitHub user Aegeaner opened a pull request:

https://github.com/apache/flink/pull/5116

[FLINK-8191] [Kafka Connector] Add a RoundRobinPartitioner to be shipped 
with the Kafka…

Add a RoundRobinPartitioner to be shipped with the Kafka connector


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number. Skip *component* if you are unsure about which is the best component.
  Typo fixes that have no associated JIRA issue should be named following 
this pattern: `[hotfix] [docs] Fix typo in event time introduction` or 
`[hotfix] [javadocs] Expand JavaDoc for PuncuatedWatermarkGenerator`.

  - Fill out the template below to describe the changes contributed by the 
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**(The sections below can be removed for hotfixes of typos)**

## What is the purpose of the change

We should perhaps consider adding a round-robin partitioner ready for use 
to be shipped with the Kafka connector, along side the already available 
FlinkFixedPartitioner.


## Brief change log

Add a `FlinkRoundRobinPartitioner` class in 
_org.apache.flink.streaming.connectors.kafka.partitioner_ package.


## Verifying this change

Verified by new added unit test `FlinkRoundRobinPartitionerTest`.

## Does this pull request potentially affect one of the following parts:

  - Dependencies (does it add or upgrade a dependency): (yes / **no**)
  - The public API, i.e., is any changed class annotated with 
`@Public(Evolving)`: (yes / **no**)
  - The serializers: (yes / **no** / don't know)
  - The runtime per-record code paths (performance sensitive): (yes / 
**no** / don't know)
  - Anything that affects deployment or recovery: JobManager (and its 
components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / **no** / don't know)
  - The S3 file system connector: (yes / **no** / don't know)

## Documentation

  - Does this pull request introduce a new feature? (**yes** / no)
  - If yes, how is the feature documented? (not applicable / docs / 
**JavaDocs** / not documented)


You can merge this pull request into a Git repository by running:

$ git pull https://github.com/Aegeaner/flink FLINK-8191

Alternatively you can review and apply these changes as the patch at:

https://github.com/apache/flink/pull/5116.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

This closes #5116


commit 67e07e82895ff680e65b23af06ccb6085f5ae0b6
Author: Aegeaner 
Date:   2017-12-04T10:49:12Z

[FLINK-8191] Add a RoundRobinPartitioner to be shipped with the Kafka 
connector




> Add a RoundRobinPartitioner to be shipped with the Kafka connector
> --
>
> Key: