Java Client DCP Uncompressed Throughput Decreased 20%

We are observing a decreased in java client dcp throughput for uncompressed data.

Test

DCP Throughput, 1 node, 250M x 1KB, Java client, compression disabled

Results

6.5.0-3126: http://perf.jenkins.couchbase.com/job/ares-dcp/371/ – 62148
6.5.0-3127: http://perf.jenkins.couchbase.com/job/ares-dcp/368/ – 48232

Report

http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=ares_650-3126_access_1275&snapshot=ares_650-3127_access_80b5

Logs for 6.5.0-3126

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-ares-dcp-371/172.23.133.11.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-ares-dcp-371/172.23.133.12.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-ares-dcp-371/172.23.133.13.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-ares-dcp-371/172.23.133.14.zip

Logs for 6.5.0-3127**

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-ares-dcp-368/172.23.133.11.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-ares-dcp-368/172.23.133.12.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-ares-dcp-368/172.23.133.13.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-ares-dcp-368/172.23.133.14.zip

Changelog for 6.5.0-3126 to 6.5.0-127

http://172.23.123.43:8000/getchangelog?product=couchbase-server&fromb=6.5.0-3126&tob=6.5.0-3127

Comment

Looks like a fix for cursor dropping may be the issue:

https://github.com/couchbase/kv_engine/commit/4b3d2019007246f1e59b3e02975fc356001e106d

The performance history of this test has a lot of volatility and the throughput for compressed version of the test increased.