https://www.mongodb.com/docs/upcoming/reference/command/fsync/#check-lock-status

There is a function in the docs page that a user can run to check the lock status - it parses currentOp output

However, when running from a mongos, the currentOp output shows output from each shard, and the fsyncLock field is inside these documents, e.g.

    {
      shard: 'shard02',
      fsyncLock: true,
      type: 'op',
      host: 'M-K4F3614CKP:30004',
      desc: 'Checkpointer',
      active: true,
      currentOpTime: '2024-05-16T17:32:45.613+10:00',
      isFromUserConnection: false,
      opid: 'shard02:4120',
      op: 'none',
      ns: '',
      redacted: false,
      command: {},
      numYields: 0,
      queues: {
        execution: { admissions: 0, totalTimeQueuedMicros: Long("0") },
        ingress: { admissions: 0, totalTimeQueuedMicros: Long("0") }
      },
      currentQueue: null,
      locks: {},
      waitingForLock: false,
      lockStats: {},
      waitingForFlowControl: false,
      flowControlStats: {}
    }

But there is no top level field called fsyncLock and so this function returns "false" when run against a mongos, even when the cluster is fsyncLocked

Please either revise the function so it works against a mongos, or add a note saying this only works when connected to a replica set (or standalone, I guess)

I think the former (revise the function so it works against a mongos) is preferred, as soon all deployments will be sharded clusters (coming in 8.3?)