I would be looking at the queries in the application to see if there are any cross-partition queries (ALLOW FILTERING or IN clauses across partitions). This looks like queries that work fine with small scale, but are hitting timeouts when the data size has increased. Also see if anyone has ad-hoc access to the cluster and is running some of those same kind of bad queries.
Sean Durity From: MyWorld <timeplus.1...@gmail.com> Sent: Tuesday, January 26, 2021 8:50 AM To: user@cassandra.apache.org Subject: [EXTERNAL] Cassandra timeouts 3.11.6 Hi, We have a cluster of 4 nodes all in one DC (apache cass version : 3.11.6). Things were working fine till last month when all of a sudden we started facing Operation time outs at client end intermittently. We have prometheus+grafana configured for monitoring. On checking we found the following points: 1. Read/Write latency at coordinator level increase at the same time on one or multiple nodes. 2. jvm_threads_current increases at the same time on one or multiple nodes. 3. Cassandra hints storage increases at the same time on one or multiple nodes. 4. Increase in Client Requests + Connection timeout with dropped messages at times. 5. Increase in connected native clients count on all nodes Things already checked : 1. No change in read/write requests. 2. No major change in table level read/write latency. 3. No spike on DB load or CPU utilization. 4. Memory usage is also normal. 5. GC Pauses are also normal. 6. No packet loss between nodes at network level On checking detailed logs, we found majorly two types of messages during timeouts. 1. HintsDispatcher : Dispatching hints from one node to other 2. READ messages were dropped in last 5000 ms: 0 internal and 1 cross node. Mean internal dropped latency: 0 ms and Mean cross-node dropped latency: 14831 ms 3. StatusLogger messages. Please suggest possible reasons for the same and action items. Regards, Ashish ________________________________ The information in this Internet Email is confidential and may be legally privileged. It is intended solely for the addressee. Access to this Email by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful. When addressed to our clients any opinions or advice contained in this Email are subject to the terms and conditions expressed in any applicable governing The Home Depot terms of business or client engagement letter. The Home Depot disclaims all responsibility and liability for the accuracy and content of this attachment and for any damages or losses arising from any inaccuracies, errors, viruses, e.g., worms, trojan horses, etc., or other items of a destructive nature, which may be contained in this attachment and shall not be liable for direct, indirect, consequential or special damages in connection with this e-mail message or its attachment.
