Add metric -- count of queries waiting for merge buffers#15025

Merged

LakshSingla merged 6 commits intoapache:masterfrom kaisun2000:feature-expose-mergebuffer-waiting-queries-count

Oct 9, 2023

+104-5

Commits on Sep 22, 2023

Add metric for the number of pending queries waiting for shared merge buffers.
Kai Sun
committed
fix static check failure; remove the registering of MergeBufferPoolMonitor by default
Kai Sun
committed
enhance the unit test to make it not flaky
Kai Sun
committed

Commits on Oct 3, 2023

Merge remote-tracking branch 'upstream/master' into feature-expose-mergebuffer-waiting-queries-count
Kai Sun
committed
revised base on feedback.
Kai Sun
committed
address Laksh's comments
Kai Sun
committed