to share this week's community update. The first real release candidate of Apache Flink 1.9.0 has been published and the developer community has moved more towards the 1.10 development cycle with more discussion threads popping up again.
As always, please feel free to add additional updates and news to this thread!
Personal Note: There will be no weekly community update in the next three weeks as I will be on vacation :). The next update will be on the 8th of September, which will then cover four weeks instead of one.
* [releases] The voting thread on RC2 for Apache Flink 1.9.0 has just started. It will be open for at least 72 hours. [1,2]
[development] Chesnay has started a discussion on splitting up Flink's main repository to tackle build time issues and an ever increasing number of pull requests. So far, the majority of answers is in favor of keeping the mono repo and tackling the problems differently via a more sophisticated build system, project structure, etc. It seems these alternatives deserve a more detailed investigation. 
* [development process] Stephan has raised the point of post-feature-freeze contributions to Flink 1.9.0 in a discussion thread on the mailing list last week. The thread also contains a few proposals e.g. to formalize the process in the future, which probably need to be discussed in separate threads in the future. 
* [resource management] Xintong has startd a discussion on FLIP-49 to improve and unify the memory configuration of TaskManagers. Its goals are to unify the memory configuration for batch and stream processing, to simplify automatically configure RocksDB and to simplify the configuration of the different memory pools. 
* [documentation] Marta has written a style guide for our documentation based on best practices and other successful Open Source projects. More feedback welcome! 
* [documentation] Myself and Fabian have recently contributed a docker-based playground to the Getting Started section of the documentation. This lead to a follow up discussion of how to publish the required Docker Images. 
* [development process] The style and quality guide has finally been published on the project website. 
* [sources] Zhijang has started a discussion to start with the integration of the SourceReader with the mailbox of the StreamTask, which is proposed as part of FLIP-27 (Refactor Source Interface). 
* [FLINK-13586] [1.8.1] The signature of org.apache.flink.api.java.ClosureCleaner#clean was changed between 1.8.0 and 1.8.1. Hence, no application calling this method compiled against Flink 1.8.0 can be run on a Flink 1.8.1 cluster. For example, this includes any application using the Kafka or Cassandra Connector. 
* [FLINK-13537] [1.8.1] [1.7.2] [1.6.4] If an exactly-once Kafka Producer is rescaled and the "pool size" (# of transactionanl ids per subtask) is changed at the same time, the transactional ids of different subtasks might overlap, which should never happen. Fortunately, users can easily avoid such a scenario until this is fixed.