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Lars Volker updated IMPALA-7486: -------------------------------- Labels: scalability (was: ) > Admit less memory on dedicated coordinator for admission control purposes > ------------------------------------------------------------------------- > > Key: IMPALA-7486 > URL: https://issues.apache.org/jira/browse/IMPALA-7486 > Project: IMPALA > Issue Type: Improvement > Components: Backend > Reporter: Tim Armstrong > Assignee: Bikramjeet Vig > Priority: Major > Labels: scalability > > Following on from IMPALA-7349, we should consider handling dedicated > coordinators specially rather than admitting a uniform amount of memory on > all backends. > The specific scenario I'm interested in targeting is the case where we a > coordinator that is executing many "lightweight" coordinator fragments, e.g. > just an ExchangeNode and PlanRootSink, plus maybe other lightweight operators > like UnionNode that don't use much memory or CPU. With the current behaviour > it's possible for a coordinator to reach capacity from the point-of-view of > admission control when at runtime it is actually very lightly loaded. > This is particularly true if coordinators and executors have different > process mem limits. This will be somewhat common since they're often deployed > on different hardware or the coordinator will have more memory dedicated to > its embedded JVM for the catalog cache. > More generally we could admit different amounts per backend depending on how > many fragments are running, but I think this incremental step would address > the most important cases and be a little easier to understand. > We may want to defer this work until we've implemented distributed runtime > filter aggregation, which will significantly reduce coordinator memory > pressure, and until we've improved distributed overadmission (since the > coordinator behaviour may help throttle overadmission ). -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-all-unsubscr...@impala.apache.org For additional commands, e-mail: issues-all-h...@impala.apache.org