hi, I recently encountered a problem about serverStatus.

in mongod's log, i can find a log like below with a lot of other slow logs(normal query&update, etc)

Fri May 1 14:01:23.248 I COMMAND [ftdc] serverStatus was very slow: { after basic: 0, after asserts: 0, after backgroundFlushing: 0, after connections: 0, after dur: 0, after extra_info: 0, after globalLock: 0, after locks: 0, after logicalSessionRecordCache: 0, after network: 0, after opLatencies: 0, after opcounters: 0, after opcountersRepl: 0, after repl: 0, after shardingStatistics: 0, after storageEngine: 0, after tcmalloc: 0, after transactions: 0, after wiredTiger: 0, at end: 8256 }

in source code, after all sections handled, before print this 'very slow' log,it handles with metrics and warnings. i don't understand why it took so long.

more details:

1.  it occurs 0-2 times a day, without any regularity in time;
2.  system load has not changed significantly; and the load is not heavy considering the resources;
3.  various resources(CPU, Mem, Disk, Network) do not seem to be the bottleneck;
4.  it happened both on primary & secondary nodes;

my question:

1.  what does is mean when 'serverStatus' slow only at end? is it reasonable?

2.  under what scenarios may cause this problem?

3. how can I locate this problem, is there any recommendation?

Thank you!