[CASSANDRA-17751] Better Behavior for GCInspector with Low Pause Time GCs

• Type: Improvement
• Status: Open
• Priority: Low
• Resolution: Unresolved
• Fix Version/s: 5.x
• Component/s: Local/Other
• Change Category: Operability
• Complexity: Low Hanging Fruit
• Platform: All
• Assignee: Unassigned
• Reporter: Reilly Brogan
• Created: 12/Jul/22 22:56
• Updated: 07/Mar/23 10:54

Description

Low pause time GCs like Shenandoah tend to be very spammy when it comes to running Cassandra with the default configuration. This is because GCInspector seems to detect that Shenandoah cycles are equivalent to GC pauses and because these cycles tend to be relatively long (in the order of 2-3 seconds in my experience) GCInspector constantly throws warnings. However, these cycle times are normal and are not an indicator of resource contention or heap pressure as the actual pause times are very short.

It would be great if Cassandra could be modified such that GCInspector had different behavior if a low pause time collector was detected as being in use (such as perhaps disabling the warning altogether).

Note that I used Shenandoah here for my example but ZGC is presumed to have similar behavior.