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https://issues.apache.org/jira/browse/FLINK-9083?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16635087#comment-16635087
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ASF GitHub Bot commented on FLINK-9083:
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jparkie opened a new pull request #6782: [FLINK-9083][Cassandra Connector] Add
async backpressure support to Cassandra Connector
URL: https://github.com/apache/flink/pull/6782
## What is the purpose of the change
This pull requests rewrites `CassandraSinkBase` to use a `Phaser` and
`Semaphore` to provide proper synchronization to support
`maxConcurrentRequests` as a new configuration. This improves the reliability
of the Cassandra Connector as it can currently overwhelm a weak Cassandra
cluster if the upstream source has very high throughput.
## Brief change log
- Rewrote `CassandraSinkBase` to use a `Phaser` and `Semaphore`.
- Expose `public void setMaxConcurrentRequests(int maxConcurrentRequests,
long timeout, TimeUnit unit)` on `CassandraSinkBase`.
- Modify `CassandraSink` with the new configuration. It currently does not
support the WAL.
- Updated the documentation about the new configuration.
## Verifying this change
This change is already covered by existing tests, such as
`CassandraSinkBaseTest` and `CassandraConnectorITCase`.
This change added tests and can be verified as follows:
- Added tests for acquiring permits from the `Semaphore` and releasing
permits from the `Semaphore` when a write succeeds or fails.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): no
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: no
- The serializers: no
- The runtime per-record code paths (performance sensitive): no
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? yes
- If yes, how is the feature documented? docs / JavaDocs
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> Add async backpressure support to Cassandra Connector
> -----------------------------------------------------
>
> Key: FLINK-9083
> URL: https://issues.apache.org/jira/browse/FLINK-9083
> Project: Flink
> Issue Type: Improvement
> Components: Cassandra Connector
> Reporter: Jacob Park
> Assignee: Jacob Park
> Priority: Minor
> Labels: pull-request-available
>
> As the CassandraSinkBase derivatives utilize async writes, they do not block
> the task to introduce any backpressure.
> I am currently using a semaphore to provide backpressure support by blocking
> at a maximum concurrent requests limit like how DataStax's Spark Cassandra
> Connector functions:
> [https://github.com/datastax/spark-cassandra-connector/blob/v2.0.7/spark-cassandra-connector/src/main/scala/com/datastax/spark/connector/writer/AsyncExecutor.scala#L18]
> This improvement has greatly improved the fault-tolerance of our Cassandra
> Sink Connector implementation on Apache Flink in production. I would like to
> contribute this feature back upstream.
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