[HDFS-14277] [SBN read] Observer benchmark results

• Type: Task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.10.0, 3.3.0
• Component/s: ha, namenode

Environment

Hardware: 4-node cluster, each node has 4 core, Xeon 2.5Ghz, 25GB memory.
Software: CentOS 7.4, CDH 6.0 + Consistent Reads from Standby, Kerberos, SSL, RPC encryption + Data Transfer Encryption, Cloudera Navigator.

• Target Version/s: 2.10.3
• Assignee: Unassigned
• Reporter: Wei-Chiu Chuang
• Created: 14/Feb/19 03:12
• Updated: 24/May/22 06:16

Description

Ran a few benchmarks and profiler (VisualVM) today on an Observer-enabled cluster. Would like to share the results with the community. The cluster has 1 Observer node.

NNThroughputBenchmark

Generate 1 million files and send fileStatus RPCs.

hadoop org.apache.hadoop.hdfs.server.namenode.NNThroughputBenchmark -fs <namenode>  -op fileStatus -threads 100 -files 1000000 -useExisting -keepResults

Kerberos, SSL, RPC encryption, Data Transfer Encryption enabled:

Node	fileStatus (Ops per sec)
Active NameNode	4865
Observer	3996

Kerberos, SSL:

Node	fileStatus (Ops per sec)
Active NameNode	7078
Observer	6459

Observation:

• due to the edit tailing overhead, Observer node consume 30% CPU utilization even if the cluster is idle.
• While Active NN has less than 1ms RPC processing time, Observer node has > 5ms RPC processing time. I am still looking for the source of the longer processing time. The longer RPC processing time may be the cause for the performance degradation compared to that of Active NN. Note the cluster has Cloudera Navigator installed which adds additional overhead to RPC processing time.
• GlobalStateIdContext#isCoordinatedCall() pops up as one of the top hotspots in the profiler. 

 

Issue Links

• is related to: HDFS-14276 [SBN read] Reduce tailing overhead
• relates to: HDFS-14822 [SBN read] Revisit GlobalStateIdContext locking when getting server state id
• relates to: HDFS-14858 [SBN read] Allow configurably enable/disable AlignmentContext on NameNode