albertogpz opened a new pull request #6478: URL: https://github.com/apache/geode/pull/6478
…on-events When group-transaction-events is set to true the SerialGatewaySenderQueue class stores those events peeked from the queue to complete transactions for a batch inside the extraPeekedIds member. This is done so that, when new events are peeked from the queue by peekAhead() to be put in a batch, the events in extraPeekedIds are skipped. Otherwise those events will be sent several times. When the remove method of SerialGatewaySenderQueue is called, the peekedIds member and the head key of the queue are updated and events from extraPeekedIds are removed if necessary. Given that the peekAhead() method first gets the currentKey (that depends on the peekedIds and the headkey) and then checks if the event to be removed is in extraPeekedIds, it could be that in between those two calls, remove() is called from another thread, causing that peekAhead() returns an event that belonged to extraPeekedIds when the currentKey was obtained but was deleted from extraPeekedIds by remove() before it was checked that the event belonged to extraPeekedIds. This provokes that an event already peeked is returned again by peekAhead() leading to duplicate events sent by the gateway sender. The solution proposed to solve this problem is to make synchronized the peekAhead() function when group-transaction-events is set given that remove() is already synchronized. This will prevent the race condition described above. Thank you for submitting a contribution to Apache Geode. In order to streamline the review of the contribution we ask you to ensure the following steps have been taken: ### For all changes: - [ ] Is there a JIRA ticket associated with this PR? Is it referenced in the commit message? - [ ] Has your PR been rebased against the latest commit within the target branch (typically `develop`)? - [ ] Is your initial contribution a single, squashed commit? - [ ] Does `gradlew build` run cleanly? - [ ] Have you written or updated unit tests to verify your changes? - [ ] If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under [ASF 2.0](http://www.apache.org/legal/resolved.html#category-a)? ### Note: Please ensure that once the PR is submitted, check Concourse for build issues and submit an update to your PR as soon as possible. If you need help, please send an email to d...@geode.apache.org. -- 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: us...@infra.apache.org
