GitHub user pnowojski opened a pull request: https://github.com/apache/flink/pull/4955
[FLINK-7978][kafka] Ensure that transactional ids will never clash ## What is the purpose of the change Previously transactional ids to use and to abort could clash between subtasks. This could lead to a race condition between initialization and writting the data, where one subtask is still initializing/aborting some transactional id while different subtask is already trying to write the data using the same transactional id. ## Brief change log First commit extracts `TransactionalIdsGenerator` logic and is a pure refactor, without any functional change. Second one is the actual fix. I would like to merge those two commits as they are, without squashing, so that a bug fix is actually easier to understand/read in the commit history. ## Verifying this change This fixes a bug and adds test coverage (`TransactionalIdsGeneratorTest`) for future regressions. ## 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/pnowojski/flink f7978 Alternatively you can review and apply these changes as the patch at: https://github.com/apache/flink/pull/4955.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 #4955 ---- commit 54c1729fed93e51f416d365c65cbd64f67c27321 Author: Piotr Nowojski <piotr.nowoj...@gmail.com> Date: 2017-11-06T13:03:16Z [hotfix][kafka] Extract TransactionalIdsGenerator class from FlinkKafkaProducer011 This is pure refactor without any functional changes. commit 96bb26e5d9289fb8393f0807936792d89138a744 Author: Piotr Nowojski <piotr.nowoj...@gmail.com> Date: 2017-11-06T13:14:01Z [FLINK-7978][kafka] Ensure that transactional ids will never clash Previously transactional ids to use and to abort could clash between subtasks. This could lead to a race condition between initialization and writting the data, where one subtask is still initializing/aborting some transactional id while different subtask is already trying to write the data using the same transactional id. ---- ---