valan4ik opened a new pull request #29809: URL: https://github.com/apache/spark/pull/29809
During the worker registration after Spark failover the following race condition may occur: (1) Master A fails and Worker attempts to reconnect to all masters (2) Master B takes over and notifies Worker (3) Worker responds by registering with Master B (4) Meanwhile, Worker's previous reconnection attempt reaches Master B, causing the same Worker to register with Master B twice This race condition was already once fixed in [SPARK-4592](https://issues.apache.org/jira/browse/SPARK-4592), but the very first connection retry was forgotten: right after the worker was losing connection to the master it was first trying to connect to both masters (usually this first request times out, because in general failover takes 10-15 seconds and many people almost never notice this problem). After the first try worker was continuing to try to reregister only with the last known master. <!-- Thanks for sending a pull request! Here are some tips for you: 1. If this is your first time, please read our contributor guidelines: https://spark.apache.org/contributing.html 2. Ensure you have added or run the appropriate tests for your PR: https://spark.apache.org/developer-tools.html 3. If the PR is unfinished, add '[WIP]' in your PR title, e.g., '[WIP][SPARK-XXXX] Your PR title ...'. 4. Be sure to keep the PR description updated to reflect all changes. 5. Please write your PR title to summarize what this PR proposes. 6. If possible, provide a concise example to reproduce the issue for a faster review. 7. If you want to add a new configuration, please read the guideline first for naming configurations in 'core/src/main/scala/org/apache/spark/internal/config/ConfigEntry.scala'. --> ### What changes were proposed in this pull request? <!-- Please clarify what changes you are proposing. The purpose of this section is to outline the changes and how this PR fixes the issue. If possible, please consider writing useful notes for better and faster reviews in your PR. See the examples below. 1. If you refactor some codes with changing classes, showing the class hierarchy will help reviewers. 2. If you fix some SQL features, you can provide some references of other DBMSes. 3. If there is design documentation, please add the link. 4. If there is a discussion in the mailing list, please add the link. --> If there was an active master before, never try to reregister with both masters. `reregisterWithMaster` function is smart to understand if it is a failover scenario and worker was already registered with some master or if it is the very first try and registration should be tried with both master. ### Why are the changes needed? <!-- Please clarify why the changes are needed. For instance, 1. If you propose a new API, clarify the use case for a new API. 2. If you fix a bug, you can clarify why it is a bug. --> If failover happens relatively, then `Duplicate worker ID` error may happen and worker gets killed. ### Does this PR introduce _any_ user-facing change? <!-- Note that it means *any* user-facing change including all aspects such as the documentation fix. If yes, please clarify the previous behavior and the change this PR proposes - provide the console output, description and/or an example to show the behavior difference if possible. If possible, please also clarify if this is a user-facing change compared to the released Spark versions or within the unreleased branches such as master. If no, write 'No'. --> No ### How was this patch tested? <!-- If tests were added, say they were added here. Please make sure to add some test cases that check the changes thoroughly including negative and positive cases if possible. If it was tested in a way different from regular unit tests, please clarify how you tested step by step, ideally copy and paste-able, so that other reviewers can test and check, and descendants can verify in the future. If tests were not added, please describe why they were not added and/or why it was difficult to add. --> This bug has a lot of concurrency and timing issues, but can be stably reproduced with the following steps: 1. To make failover really fast changes from https://github.com/apache/spark/pull/26598 can be used 2. Start several contexts 3. Without the patch during failover some workers will always get lost ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
