Summary

Add Statistics and logs to get insight into dhandle list composition

Offer

If anyone wants to add statistics or logs related to dhandles, add them to this branch, wt-6974-dhandle-stats. I will handle the code review, and commit.

Motivation

There have been cases where we see active dhandles grow to a large number while the files currently open (and sometimes total collections present at the moment) is much smaller. Although the dhandles are used to represent more internal structures than just the btrees alone, the common workloads generally see a proportional correlation between the total collections on the system, open files at a given instance and the active dhandles.

Given that we have seen a lot of issues in this area, it will be useful to have more insights into what dhandles are active in the system. Statistics around their creation, their types, etc and any logs would be helpful.

This ticket will explore ideas to get more insights in this area.