CounterMutationStage and ViewMutationStage metrics are missing in Cassandra 4.0

Those metrics are still there. The issue though, is that they expose their data "lazily." Which basically means, they won't show at all when the value is zero. Once you start writing to counters or views, those metrics execute their "lazy initialization," and only then are they exposed. I tested this out using Cassandra 4.0 beta4.

Running a baseline nodetool tpstats | head -n 4:

Pool Name                    Active Pending Completed Blocked All time blocked
MutationStage                0      0       1         0       0
ReadStage                    0      0       27        0       0
CompactionExecutor           0      0       41        0       0

Next, I'll create a simple counter table.

CREATE TABLE games_popularity (game text PRIMARY KEY, popularity counter);

I'll increment the counter a few times and SELECT it.

aploetz@cqlsh> SELECT * FROM stackoverflow.games_popularity ;

 game           | popularity
----------------+------------
 Cyberpunk 2077 |          3

(1 rows)

Now rerunning the nodetool tpstats | head -n 4 indeed show CounterMutationStage:

Pool Name                    Active Pending Completed Blocked All time blocked
MutationStage                0      0       12        0       0
CounterMutationStage         0      0       3         0       0
ReadStage                    0      0       96        0       0

Note that in 4.0 these metrics are also exposed in the system_view.thread_pools virtual table, which you can view with SELECT * FROM system_views.thread_pools;.

Thanks to the good work that have been done by Cassandra developers, the metrics are now lazy initialised to improve the performance.

The best way to "wake up" all lazy metrics is:

nodetool getconcurrency