This fix is to handle a very specific race condition scenario as described here:
Subscription HA is enabled and a server is providing a client queue image to a peer (serializing the queue). Meanwhile, a client is also just finished client subscription registration with that same server and is recalculating its filter info to determine if the client needs the event. Recalculating the filter info results in the client message in the HAContainer to be mutated, which causes a ConcurrentModificationException to occur in the GII provider thread. The fix we landed on is to make a copy of the client update message when recalculating the filter info in the drain logic from the client registration queue. This guarantees that there will be no shared state between the GII thread and the client registration thread, and it also covers the case that multiple clients are calculating the filter info on the same event and potentially in contention. Co-authored-by: Ryan McMahon <[email protected]> Co-authored-by: Donal Evans <[email protected]> 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: - [X] Is there a JIRA ticket associated with this PR? Is it referenced in the commit message? - [X] Has your PR been rebased against the latest commit within the target branch (typically `develop`)? - [X] Is your initial contribution a single, squashed commit? - [X] Does `gradlew build` run cleanly? - [X] Have you written or updated unit tests to verify your changes? - [N/A] 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 [email protected]. [ Full content available at: https://github.com/apache/geode/pull/3939 ] This message was relayed via gitbox.apache.org for [email protected]
