What is the significance of jetty.httpConfig.headerCacheSize in jetty.xml

Question

I am upgrading jetty version from jetty-9.4.14.v20181114 to jetty-9.4.24.v20191120. and attribute(jetty.httpConfig.headerCacheSize in jetty.xml) value is decreased(4096 to 1024).

Is there any performance reason or some other reasons for reducing it.

Answer 1

Jetty is open source. So the question can easily be answered by following these steps:

1. Find the source code
2. Find the location of the change in the source code
3. See commit message with hopefully linked issue/bug report

This leads to Jetty issue #2709, comment by Greg Wilkins:

We have some feedback that 4kb is frequently wasting memory. Trading the PR, it seams that 1k would have been sufficient, so we should probably dial back to that.