[IMPROVED] LoadNextMsg for wildcard consumers with millions of subjects #5710
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We had a use case with millions of subjects and the last sequence checked being in the next to the last block. The consumer had a wildcard that matched lots of entries that were behind where we were. This would burn alot of cpu and when a stream had lots of consumers and they shift leadership this would introduce some instability due to all the cpu cycles. Signed-off-by: Derek Collison <derek@nats.io>
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Includes the following: * #5602 * #5672 * #5668 * #5607 * #5687 * #5695 * #5697 * #5704 * #5706 * #5709 * #5710 * #5713 * #5719 Some PRs specifically excluded: * #5707 — based on a 2.11 NRG PR * #5690 — continue to allow Go 1.20 for 2.10.x * Various other NRG PRs which are higher risk and destined for 2.11 instead
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When LoadNextMsg misses, make sure to consult psim but conservatively.
We had a use case with millions of subjects and the last sequence checked being in the next to the last block. The consumer had a wildcard that matched lots of entries that were behind where we were. This would burn alot of cpu and when a stream had lots of consumers and they shift leadership this would introduce some instability due to all the cpu cycles.
Signed-off-by: Derek Collison derek@nats.io