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David Alves updated KUDU-1703: ------------------------------ Issue Type: Sub-task (was: Improvement) Parent: KUDU-430 > Handle lagging replicas for snapshot reads > ------------------------------------------ > > Key: KUDU-1703 > URL: https://issues.apache.org/jira/browse/KUDU-1703 > Project: Kudu > Issue Type: Sub-task > Affects Versions: 1.1.0 > Reporter: David Alves > > When we fix safe time advancement, replicas will start to block on snapshot > scans for arbitrary amounts of time, waiting to have a consistent view of the > world at that timestamp before serving the scan. > This will be a serious problem for lagging replicas, which might be several > seconds or even minutes behind. Moreover in the absence of writes, the same > will happen even for non-lagging replicas, which will have their safe times > updated only when the leader heartbeats. > We need to at least make sure that: > - Blocked scanner threads are not starving other work. > - If the replica's safe time is lagging by a lot, the replica refuses to do > the scan. > We might also consider other optimizations (like pinging the leader). -- This message was sent by Atlassian JIRA (v6.3.4#6332)