*Setup:* I have a Cassandra cluster running in 3 datacenters with 3 nodes each (total 9 nodes), hosted on GCP. • *Replication Factor:* 3-3-3 • *Compaction Strategy:* LeveledCompactionStrategy • *Heap Memory:* 10 GB (Total allocated memory: 32 GB) • *Off-heap Memory:* around 4 GB • *Workload:* ~1.5K writes/s per node, ~100 reads/s per node (both using LOCAL_QUORUM) *Issue:* I am observing short-lived memory spikes where total memory usage jumps from 44% to 85%. These occur periodically and last for a short period. After monitoring tpstats, I noticed that compaction threads are running during these spikes. While I understand that compaction is a fundamental process, these memory spikes make capacity planning difficult. I tried adjusting the following settings, but they did not have any effect on the spikes: • compaction_throughput_mb_per_sec • concurrent_compactors *Questions:* 1. Are there other settings I can tune to reduce memory spikes? 2. Could something else be causing these spikes apart from compaction?
Would appreciate any insights on how to smooth out memory usage. - vignesh
