1. globalLock,关键是看一下PRIMARY节点上的参数
"globalLock" : {
                                "totalTime" : 47279680356,
                                "lockTime" : 1586763,
                                "ratio" : 0.00003356120405324679,
                                "currentQueue" : {
                                                "total" : 0,
                                                "readers" : 0,
                                                "writers" : 0
                                },
                                "activeClients" : {
                                                "total" : 2,
                                                "readers" : 2,
                                                "writers" : 0
                                }
                },

activeClients表示中可以看出slave有两个,这个值在slave上始终为0
2. connections客户端连接数
Master上的
"connections" : {
        "current" : 9,
        "available" : 810
},
Slave上的
"connections" : {
     "current" : 16,
     "available" : 803
},
在客户端增加读取线程后,Master上不会变,而Slave上会增加

3. opcounters
Master上
"opcounters" : {
        "insert" : 7,
        "query" : 1215,
        "update" : 33,
        "delete" : 1,
        "getmore" : 32558,
        "command" : 48141
},
Slave上
"opcounters" : {
             "insert" : 0,
             "query" : 4971,
             "update" : 0,
             "delete" : 0,
             "getmore" : 0,
             "command" : 44342
},
可以看到insert、update、delete是在Master上,查询是在slave上,可以检查master-slave设置是否正确,注意要先执行过rs.slaveOk()