版本3.4.19

在mongo SECONDARY节点中有大量的 serverStatus was very slow，在空闲时间也有，主节点没有这种信息。oplog大小设置的是5G，很够用也不紧张，看了io 内存 cpu都不忙，不知道是怎么原因造成的，请大神提供一点分析思路。

2020-03-27T17:33:37.467+0800 I COMMAND [ftdc] serverStatus was very slow: { after basic: 0, after asserts: 0, after backgroundFlushing: 0, after connections: 0, after dur:0,

after encryptionAtRest: 3340, after extra_info: 3340, after globalLock: 3340, after locks: 3340, after network: 3340, after opLatencies: 3340, after opcounters: 3340,

after opcountersRepl: 3340, after repl: 3340, after security: 3340, after shardingStatistics: 3340, after storageEngine: 3340, after tcmalloc: 3340,

after transportSecurity: 3340, after wiredTiger: 3340, at end: 3340 }

2020-03-27T17:34:37.645+0800 I COMMAND [ftdc] serverStatus was very slow: { after basic: 0, after asserts: 0, after backgroundFlushing: 0, after connections: 0, after dur:0,

after encryptionAtRest: 0, after extra_info: 3336, after globalLock: 3336, after locks: 3336, after network: 3336, after opLatencies: 3336, after opcounters: 3336,

after opcountersRepl: 3336, after repl: 3336, after security: 3336, after shardingStatistics: 3336, after storageEngine: 3336, after tcmalloc: 3336, after transportSecurity: 3336,

after wiredTiger: 3336, at end: 3336 }