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Chris Nauroth updated HDFS-9311: -------------------------------- Resolution: Fixed Hadoop Flags: Reviewed Fix Version/s: 2.8.0 Status: Resolved (was: Patch Available) Jitendra, thank you for the code review. I cannot repro the test failures from the last Jenkins run. The whitespace check flagged on lines that are unchanged in my patch, but I took its advice anyway and used {{git apply --whitespace=fix}}. I have committed this to trunk and branch-2. > Support optional offload of NameNode HA service health checks to a separate > RPC server. > --------------------------------------------------------------------------------------- > > Key: HDFS-9311 > URL: https://issues.apache.org/jira/browse/HDFS-9311 > Project: Hadoop HDFS > Issue Type: Improvement > Components: ha, namenode > Reporter: Chris Nauroth > Assignee: Chris Nauroth > Fix For: 2.8.0 > > Attachments: HDFS-9311.001.patch, HDFS-9311.002.patch, > HDFS-9311.003.patch > > > When a NameNode is overwhelmed with load, it can lead to resource exhaustion > of the RPC handler pools (both client-facing and service-facing). > Eventually, this blocks the health check RPC issued from ZKFC, which triggers > a failover. Depending on fencing configuration, the former active NameNode > may be killed. In an overloaded situation, the new active NameNode is likely > to suffer the same fate, because client load patterns don't change after the > failover. This can degenerate into flapping between the 2 NameNodes without > real recovery. If a NameNode had been killed by fencing, then it would have > to transition through safe mode, further delaying time to recovery. > This issue proposes a separate, optional RPC server at the NameNode for > isolating the HA health checks. These health checks are lightweight > operations that do not suffer from contention issues on the namesystem lock > or other shared resources. Isolating the RPC handlers is sufficient to avoid > this situation. -- This message was sent by Atlassian JIRA (v6.3.4#6332)