# Slow cluster operations (\_cat/nodes time out) **URL:** \ **Category:** Elasticsearch\ **Created:** [August 28, 2019, 8:54pm UTC](https://discuss.elastic.co/t/slow-cluster-operations-cat-nodes-time-out/197224 "2019-08-28T20:54:50Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![hunsw](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hunsw/32/93637_2.png) [@hunsw](https://discuss.elastic.co/u/hunsw)\ **Post date:** [August 28, 2019, 8:54pm UTC](https://discuss.elastic.co/t/slow-cluster-operations-cat-nodes-time-out/197224/1 "2019-08-28T20:54:50Z")
Hey all, This is a fairly complex problem I'm facing for two days now. **SYMPTOMS** The main symptom from the admin perspective is the time out of the \_cat APIs, e.g. \_cat/nodes and slow user logins in Kibana. Sometime a \_cat/nodes call takes 45-90 seconds or more to complete. Searches are fast. **SETUP** The setup is: 3 master 12 data nodes (9 hot, 3 warm), 2 client nodes (kibana) - Searchguard security 10k shards, 3k indices. Some of the indices (cc. 10 pct) are shrunk and frozen. **FURTHER INFO** 3 data nodes are receiving events from Logstash instances and one of them is busy rejecting invalid JSON data (cannot put a JSON into a text field), one of them has a threadpool queue full with managament events. This latter one has gc kicking in every few minutes with 3-400ms/1s overhead, but Cerebro shows only a cc. 40% heap usage. (It has 24 GB heap allocated.) A cluster restart solves the problem intermittently then everything starts to slow down again. Hot threads is not very helpful to me, transport\_worker threads are culprits where there is high cpu usage. Otherwise Cerebro shows a green and working cluster. One more thing I noticed: shard recovery after cluster restart... especially after it got to 'yellow' state was painfully slow. \_cat/threadpool shows 0 everywhere except for the 2 aforementioned nodes: datanode1.write - 1 active, 3509 rejected datanode2.management - 1-5 active, 50-300 queued rest of the nodes - 0 or 1 active 0 queue 0 rejected Any idea/advice to where to go from here? What are those queued management operations, can I check/view them somehow? ---
**Author:** ![hunsw](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hunsw/32/93637_2.png) [@hunsw](https://discuss.elastic.co/u/hunsw)\ **Post date:** [September 11, 2019, 10:14am UTC](https://discuss.elastic.co/t/slow-cluster-operations-cat-nodes-time-out/197224/2 "2019-09-11T10:14:01Z")
It looks like that when these slowdowns occur, the management thread pool has a quite large queue on one of the data nodes: nodename name active queue rejected datanode2 management 5 1543 0 Can I somehow view what tasks are waiting in the queue? Or at least check a doc/page where the tasks that management threads are responsible for are listed? ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [October 9, 2019, 10:14am UTC](https://discuss.elastic.co/t/slow-cluster-operations-cat-nodes-time-out/197224/3 "2019-10-09T10:14:59Z")
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