Initialize pool from scratch after TableGC.Close

[mhamza15]

Description

When re-opening a TableGC's pool, initialize a new pool rather than reusing the existing pool instance. This is to help prevent issues where Close fails and the pool is left in an inconsistent state, causing any subsequent Closes (such as during PlannedReparentShard) to fail.

Related Issue(s)

Closes #18202

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
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Deployment Notes

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[mhamza15]

I have not yet been able to reproduce this in a test, but will be testing it on a cluster that is "stuck" in this state and PlannedReparentShard fail.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.47%. Comparing base (c3daef3) to head (ce060d3).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #18281   +/-   ##
=======================================
  Coverage   67.46%   67.47%           
=======================================
  Files        1602     1602           
  Lines      262245   262254    +9     
=======================================
+ Hits       176930   176944   +14     
+ Misses      85315    85310    -5     

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[GrahamCampbell]

Does this need backport labels?

[mhamza15]

Does this need backport labels?

Yep, was wrangling with some tests before opening this up for review. Should be all supported versions.

I've tested it on one of our clusters and PRS has been successful a few times. I can't definitively say this fixed it, but the bug does happen most of the time so it gives us a decent level of confidence.

[deepthi]

Will we still get metrics recorded correctly?

[mhamza15]

At first I had thought so, but on a second glance, this new instance will not have the timings set up properly. Was getting this error when reinitializing the pool:

panic: Reuse of exported var name: TableGCPoolGetConnTime

Will come up with a different way.

[mhamza15]

Changed. The expvar package in Go doesn't allow deleting a registered var, so I instead chose to skip re-registering an already registered var.

[mhamza15]

Looking at test failures

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[github-actions]

This PR was closed because it has been stale for 7 days with no activity.