[#2196] Improve queue consumer starvation under low configuration#2197
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[#2196] Improve queue consumer starvation under low configuration#2197mattrpav wants to merge 2 commits into
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…figuration Test demonstrates that stalled low-priority network consumers with saturated prefetch throttle a normal-priority app consumer's throughput by 5-20x. Root cause: Queue.doPageInForDispatch() uses dispatchPendingList.size() against maxPageSize, so messages stuck behind full network consumers block page-in for all consumers. The test assertion (slowdownFactor <= 3.0) is expected to FAIL against the current code, proving the bug exists. The subsequent fix commit will make it pass.
…l prefetch Queue.doPageInForDispatch() used pagedInPendingSize < maxPageSize as the sole gate for paging in messages from the store. When low-priority network consumers had saturated prefetch (not acking), their undispatched messages accumulated in dispatchPendingList, counting against maxPageSize and blocking page-in for all consumers — including higher-priority app consumers with available prefetch capacity. Two changes: 1. When pagedInPendingSize >= maxPageSize, cap toPageIn to what consumers can actually accept (getConsumerMessageCountBeforeFull) 2. Allow page-in when any consumer has available prefetch capacity, even if pagedInPendingSize >= maxPageSize
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Run the test before the fix and observe:
Test run after fix:
edit: Tests passed, except for assembly on an address-in-use bind error. Re-running tests to get a green checkmark