Fix race condition: prevent selection of dead connection pools during node failures#3
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sagarrohankar-bsft wants to merge 1 commit intobsft-mainfrom
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…failures Add synchronous alive checks to filter out terminated pools before selection. This fixes a race condition where pools could be selected during the async termination window after a StatusChange DOWN event. Changes: - Add filter_alive_pools/1 to check Process.alive? before pool selection - Add alive check to random_connections/1 for token ring sync - Ensures retry logic only selects from healthy, running pools Fixes race condition observed when Scylla nodes fail under load, where terminated pools remained in ConnectionRegistry during async shutdown.
merajblueshift
approved these changes
Dec 8, 2025
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Problem
When a Scylla node fails, there's a race condition where terminated connection pools can still be selected during the async shutdown window. This happens because:
StatusChange DOWNevent triggers asyncterminate_child/2ConnectionRegistryduring terminationSolution
Add synchronous
Process.alive?/1checks to filter out dead pools before selection:filter_alive_pools/1inlib/xandra/cluster.ex(pool selection)random_connections/1inlib/xandra/clusters/cluster.ex(token ring sync)This ensures pools are only selected if the process is actually running, even if still registered.