These release notes discuss important aspects, such as configuration, behavior, or dependencies, that changed between Flink 1.4 and Flink 1.5. Please read these notes carefully if you are planning to upgrade your Flink version to 1.5.
jobmanager.sh script was reworked which removed the execution mode parameter (
Now it has the following syntax:
jobmanager.sh ((start|start-foreground) [host] [webui-port])|stop|stop-all.
Consequently, all external scripts need to remove the execution mode parameter when calling
Otherwise, the execution mode (
cluster) will be interpreted as the host name of the started process.
This can lead to connectivity problems between Flink’s components.
Flink’s reworked cluster and job deployment component improves the integration with resource managers and enables dynamic resource allocation. One result of these changes is, that you no longer have to specify the number of containers when submitting applications to YARN and Mesos. Flink will automatically determine the number of containers from the parallelism of the application.
Although the deployment logic was completely reworked, we aimed to not unnecessarily change the previous behavior to enable a smooth transition. Nonetheless, there are a few options that you should update in your
conf/flink-conf.yaml or know about.
Please report any problems or possible improvements that you notice to the Flink community, either by posting to a mailing list or by opening a JIRA issue.
Note: We plan to remove the legacy mode in the next release.
The changes on the networking stack for credit-based flow control and improved latency affect the configuration of network buffers. In a nutshell, the networking stack can require more memory to run applications. Hence, you might need to adjust the network configuration of your Flink setup.
There are two ways to address problems of job submissions that fail due to lack of network buffers.
Please consult the section about network buffer configuration in the Flink documentation for details. In case you experience issues with the new credit-based flow control mode, you can disable flow control by setting
Note: We plan to remove the old model and this configuration in the next release.
We removed the automatic Hadoop classpath discovery via the Hadoop binary. If you want Flink to pick up the Hadoop classpath you have to export
HADOOP_CLASSPATH. On cloud environments and most Hadoop distributions you would do
export HADOOP_CLASSPATH=`hadoop classpath`.
Due to a limitation in Netty’s
SsLHandler (v4.0.27), it does not work well together with GCM enabled cypher suites.
It can cause transmission failures between Flink TaskManager’s which manifest in a
Therefore, it is highly recommended to either set the
security.ssl.algorithms configuration to
TLS_RSA_WITH_AES_128_CBC_SHA when enabling SSL encryption or to disable SSL encryption between TaskManagers via
In an effort to harmonize, extend, and improve the REST API, a few handlers and return values were changed.
/joboverview) and returns a list of job details instead of the pre-grouped view of running, finished, cancelled and failed jobs.
Please check the REST API documentation for details.
The Flink Kafka Producer now flushes on checkpoints by default. Prior to version 1.5, the behaviour was disabled by default and users had to explicitly call
setFlushOnCheckpoints(true) on the producer to enable it.
The Kinesis dependencies of Flink’s Kinesis connector have been updated to the following versions.
<aws.sdk.version>1.11.319</aws.sdk.version> <aws.kinesis-kcl.version>1.9.0</aws.kinesis-kcl.version> <aws.kinesis-kpl.version>0.12.9</aws.kinesis-kcl.version>
Flink’s non-default failover strategies are still a very experimental feature which come with a set of limitations.
You should only use this feature if you are executing a stateless streaming job.
In any other cases, it is highly recommended to remove the config option
jobmanager.execution.failover-strategy from your
flink-conf.yaml or set it to
In order to avoid future problems, this feature has been removed from the documentation until it will be fixed. See FLINK-10880 for more details.