Thread Group Iterations getting unexpected warning - Existing CookieManager HTTP Cookie Manager superseded by HTTP Cookie Manager

[cewinter]

Expected behavior

Cookie Manager added for the Thread Group and Cleared on each iteration. Cookie Manager used for all iterations of the thread group.

Actual behavior

Getting warning of "HTTPSamplerBase: Existing CookieManager HTTP Cookie Manager superseded by HTTP Cookie Manager" for in this example all the http requests except the first iteration but there is only 1 Cookie Manager.

Attached below is a simplified way to reproduce the problem we've seen. There is only one Cookie Manager within the whole jmx in the threadgroup no others at any other levels.

Steps to reproduce the problem

cookiemanagerwarningerror2.jmx.zip

JMeter Version

5.6.3

Java Version

openjdk 21.0.7 2025-04-15

OS Version

macOS Sequoia Version 15.5

[cewinter]

Have run the same jmx on 5.5 same java and same OS and the warnings don't appear

[stwi-gh]

If the cookie manager being applied (multiple times) every time a thread loops, could this be impacting throughput? On a long test with a large number of threads this could potentially have an impact.