isMaster sleeping for MaxAwaitTimeMS

Ops and Admin
1

Hi ,

Using Mongo 5.0 but the behavior is same in 4.4 as well.
When i check the queries running longer than 3sec i see few queries which are triggered from NetworkInterfaceTL are causing more than 9sec . When i check the code, mongoDB is sending isMaster:1 query with MaxAwaitTimeMS as 10000 which is 10s. I see the changes are introduced but no clue why https://jira.mongodb.org/browse/SERVER-44509.

We are seeing high load avg and response time issues with mongoDB. So as part of the debugging found these long running queries. Does it cause any issues that we are dealing ?


"host" : "nd8bwa8psm09va:27717",
                "desc" : "conn1176629",
                "connectionId" : 1176629,
                "client" : "172.26.243.81:42776",
                "clientMetadata" : {
                        "driver" : {
                                "name" : "NetworkInterfaceTL",
                                "version" : "4.4.18"
                        },
                        "os" : {
                                "type" : "Linux",
                                "name" : "AlmaLinux release 8.6 (Sky Tiger)",
                                "architecture" : "x86_64",
                                "version" : "Kernel 4.18.0-372.32.1.el8_6.x86_64"
                        }
                },
                "active" : true,
                "currentOpTime" : "2023-12-22T01:50:11.826+00:00",
                "effectiveUsers" : [
                        {
                                "user" : "__system",
                                "db" : "local"
                        }
                ],
                "opid" : -1908665977,
                "secs_running" : NumberLong(9),
                "microsecs_running" : NumberLong(9450509),
                "op" : "command",
                "ns" : "admin.$cmd",
                "command" : {
                        "isMaster" : 1,
                        "maxAwaitTimeMS" : NumberLong(10000),
                        "topologyVersion" : {
                                "processId" : ObjectId("6565de3abda8c8bd1d74c672"),
                                "counter" : NumberLong(78)
                        },
                        "internalClient" : {
2

The duration of the isMaster is likely due to the high loadavg rather than causing it.

Review Production Notes and Operations Checklist to ensure your system is production ready.

https://www.mongodb.com/docs/manual/administration/production-notes/
https://www.mongodb.com/docs/manual/administration/production-checklist-operations/