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Dimitris Tsirogiannis resolved IMPALA-3807. ------------------------------------------- Resolution: Fixed Fix Version/s: Impala 2.9.0 > Introduce support for dedicated Impalad coordinator(s) > ------------------------------------------------------ > > Key: IMPALA-3807 > URL: https://issues.apache.org/jira/browse/IMPALA-3807 > Project: IMPALA > Issue Type: New Feature > Components: Backend > Affects Versions: Impala 2.8.0 > Reporter: Mostafa Mokhtar > Labels: performance, scalability > Fix For: Impala 2.9.0 > > > After running large scale concurrent tests it was obvious that a dedicated > coordinator. > During the concurrency tests resource utilization in terms of CPU, Memory and > Network were significantly higher than other worker nodes. > The increase in resource utilization was mostly due to > * Sending exec plan fragment to remote fragments, ExecPlanFragment can become > very large for complex queries with lots of files & partitions > * Runtime filters consume lots of untracked memory when the bloom filters are > aggregated > * Runtime filters consume lots of Network throughput on the coordinator as it > receives, aggregates and sends the filters > * Aggregating RunProfile counters > * When CPU utilization on the coordinator is high remote fragments > occasionally fail with "Couldn't get a client for > impala-8-2.vpc.cloudera.com:22000 Reason: Couldn't open transport for > impala-compete-8-2.vpc.cloudera.com:22000 (connect() failed: Connection timed > out)" > * Slow start of remote query fragments specially when the coordinator node is > under heavy load > * Admission control counters can become out of sync when using multiple > coordinators > Metadata should naturally benefit from running a dedicated coordinator as > metadata is less likely to become out of sync and one day we can get rid of > expensive catalog updates. > The dedicated coordinator should only run the +Coordinator Fragment+ and not > participate in any scans, aggs etc.. > This work will require CM support. > Running a dedicated coordinator significantly improved performance of > complex TPC-DS queries > |Query||Baseline (seconds)||Dedicated coord (seconds)||Speedup %| > |74|73|43|70%| > |75|152|91|67%| > |4|127|78|63%| > |25|53|34|56%| > |95|35|23|52%| > |11|82|54|52%| > |85|37|25|48%| > |17|71|48|48%| > |64|147|101|46%| > |29|65|47|38%| > |72|408|312|31%| > |18|36|28|29%| > |44|36|28|29%| > |60|6|5|20%| > |77|12|10|20%| > |50|43|36|19%| > |5|60|51|18%| > |81|14|12|17%| > |23|198|170|16%| > |80|29|25|16%| > |35|22|19|16%| > |68|15|13|15%| > |78|551|486|13%| > |31|36|32|13%| -- This message was sent by Atlassian JIRA (v6.4.14#64029)