I've recently migrated a medium sized cluster (15TB, 25B documents) from
7.8.0 and noticed the heap constantly fluctuates between <1GB and the maximum set size (22GB). However the cluster is working perfectly fine and is noticeably faster after the upgrade, so I decided to let it go for the moment.
Yesterday I had to start a new single-server cluster with only a few indices with about 1000 documents each. It's practically empty. Indexing and searching are rare too (few events/minute), but I noticed the same pattern here too. Again, everything is stable and works fast.
The VM has 16G RAM and ES is given 8GB (
Here's how the graphs look like (1 hour period):
I don't think it's a monitoring glitch, because I can confirm the same observations using Cerebro.
Here's my elasticsearch.yml:
cluster.name:deduplicator cluster.initial_master_nodes: ["deduplicator"] node.name:deduplicator node.master: true node.data: true indices.query.bool.max_clause_count: 50000 network.host: 0.0.0.0 http.max_content_length: 1024mb path.logs: /var/log/elasticsearch path.data: /home/elasticsearch/
-Xmx is changed in jvm.options.
OS is CentOS 8 on the new cluster and CentOS 7 on the old one.
I read a lot of articles and topics on heap usage, but never saw this particular issue. Can you give me some directions where to look? Thanks!