MongoDB性能监控(3)—数据库命令
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1、概述
- 前面两个帖子有介绍MongoDB的监控命令mongostat和mongotop命令，接下来将会介绍三个MongoDB内部状态的数据库命令，它们是所有MongoDB监控应用程序的基础。
2、serverStatus
- serverStatus命令的输出内容非常的丰富，统计的所有信息中包含页错误、B树访问率、打开连接数，以及总的插入、更新、查询和删除等信息内容。
- 执行命令如下（由于内容过多，只选取部分内容）：
MongoDB Enterprise testrs:PRIMARY> use admin switched to db admin MongoDB Enterprise testrs:PRIMARY> db.runCommand({serverStatus: 1}) { "host" : "ggtest1:27018", "advisoryHostFQDNs" : [ ], "version" : "3.2.8", "process" : "mongod", "pid" : NumberLong(20984), "uptime" : 1303366, "uptimeMillis" : NumberLong(1303365659), "uptimeEstimate" : 1250796, "localTime" : ISODate("2016-11-03T07:48:29.207Z"), "asserts" : { "regular" : 0, "warning" : 0, "msg" : 0, "user" : 3, "rollovers" : 0 }, "connections" : { "current" : 9, "available" : 810, "totalCreated" : NumberLong(4509) }, "extra_info" : { "note" : "fields vary by platform", "heap_usage_bytes" : 337442568, "page_faults" : 16 }, "globalLock" : { "totalTime" : NumberLong("1303365668000"), "currentQueue" : { "total" : 0, "readers" : 0, "writers" : 0 }, "activeClients" : { "total" : 24, "readers" : 0, "writers" : 0 } }, "locks" : { "Global" : { "acquireCount" : { "r" : NumberLong(21674384), "w" : NumberLong(666709), "R" : NumberLong(5), "W" : NumberLong(7) } }, "Database" : {其中，globalLock：部分很重要，因它揭示了服务器花在写锁上的总时间。
currentQueue：的统计信息中，如果有大量的读或写等在队列中，那么就意味着需要进行某种优化了。
mem：部分显示了mongod进程是如何使用内存的。bits字段说明这是一台64位或是32位的机器；resident是MongoDB所占用的物理内存数量；virtual是进程所映射的虚拟内存的兆字节数；mapped是virtual的子集，标明那些内存里有多少是只用来映射文件的。
每个版本的MongoDB里，serverStatus的输出结果都会有所变化并得以改进。
3、top
top命令会显示每个数据库的操作计数器。如果应用程序使用了多个物理数据库，或者想看看操作的平均耗时，那么这是一个很有用的命令。
下面是一些输出内容：
MongoDB Enterprise testrs:PRIMARY> db.runCommand({top: 1}) { "totals" : { "note" : "all times in microseconds", "admin.person3" : { "total" : { "time" : 44166108, "count" : 284542 }, "readLock" : { "time" : 3279, "count" : 339 }, "writeLock" : { "time" : 44162829, "count" : 284203 }, "queries" : { "time" : 123, "count" : 1 }, "getmore" : { "time" : 0, "count" : 0 }, "insert" : { "time" : 44162829, "count" : 284203 }, "update" : { "time" : 0, "count" : 0 }, "remove" : { "time" : 0, "count" : 0 }, "commands" : { "time" : 0, "count" : 0 } }, "admin.person4" : { "total" : { "time" : 13055754, "count" : 49141 }, "readLock" : { "time" : 30908, "count" : 254 }, "writeLock" : { "time" : 13024846,- 此处可以发现写锁花费的时间很多，这样就可以查看是否需要对写操作进行优化了。
4、db.currentOp()
db.currentOp()命令可以查看MongoDB当前正在运行的所有操作，以及正在等待运行的操作信息。
下面是该命令的输出内容：
MongoDB Enterprise testrs:PRIMARY> db.currentOp() { "inprog" : [ { "desc" : "conn4499", "threadId" : "1638234432", "connectionId" : 4499, "client" : "10.130.170.12:54230", "active" : true, "opid" : 5677478, "secs_running" : 1, "microsecs_running" : NumberLong(1937503), "op" : "getmore", "ns" : "local.oplog.rs", "query" : { "getMore" : NumberLong("15148536861"), "collection" : "oplog.rs", "maxTimeMS" : NumberLong(5000), "term" : NumberLong(111), "lastKnownCommittedOpTime" : { "ts" : Timestamp(1478159326, 293), "t" : NumberLong(111) } }, "numYields" : 0, "locks" : { }, "waitingForLock" : false, "lockStats" : { "Global" : { "acquireCount" : { "r" : NumberLong(2) } }, "Database" : { "acquireCount" : { "r" : NumberLong(1) } }, "oplog" : { "acquireCount" : { "r" : NumberLong(1) } } } }, { "desc" : "rsSync", "threadId" : "1289922880", "active" : true, "opid" : 8, "secs_running" : 1304727, "microsecs_running" : NumberLong("1304727618937"), "op" : "none", "ns" : "local.replset.minvalid", "query" : { }, "numYields" : 0, "locks" : { }, "waitingForLock" : false, "lockStats" : { "Global" : { "acquireCount" : { "r" : NumberLong(26), "w" : NumberLong(4), "R" : NumberLong(5), "W" : NumberLong(2) } }, "Database" : { "acquireCount" : { "r" : NumberLong(8), "w" : NumberLong(1), "W" : NumberLong(3) } }, "Collection" : { "acquireCount" : { "r" : NumberLong(7) } }, "Metadata" : { "acquireCount" : { "w" : NumberLong(1) } }, "oplog" : { "acquireCount" : { "r" : NumberLong(1), "w" : NumberLong(1) } } } }, { "desc" : "WT RecordStoreThread: local.oplog.rs", "threadId" : "1164032320", "active" : true, "opid" : 24, "secs_running" : 1304726, "microsecs_running" : NumberLong("1304726793327"), "op" : "none", "ns" : "local.oplog.rs", "query" : { }, "numYields" : 0, "locks" : { }, "waitingForLock" : false, "lockStats" : { "Global" : { "acquireCount" : { "r" : NumberLong(1), "w" : NumberLong(1) } }, "Database" : { "acquireCount" : { "w" : NumberLong(1) } }, "oplog" : { "acquireCount" : { "w" : NumberLong(1) } } } }, { "desc" : "SyncSourceFeedback", "threadId" : "1306708288", "active" : true, "opid" : 927, "op" : "none", "ns" : "", "query" : { }, "numYields" : 0, "locks" : { }, "waitingForLock" : false, "lockStats" : { } }, { "desc" : "conn4508", "threadId" : "1085319488", "connectionId" : 4508, "client" : "10.130.170.11:27023", "active" : true, "opid" : 5677485, "secs_running" : 0, "microsecs_running" : NumberLong(76), "op" : "command", "ns" : "admin.$cmd", "query" : { "currentOp" : 1 }, "numYields" : 0, "locks" : { }, "waitingForLock" : false, "lockStats" : { } }, { "desc" : "ReplBatcher", "threadId" : "1608845632", "active" : true, "opid" : 9, "op" : "none", "ns" : "", "query" : { }, "numYields" : 0, "locks" : { }, "waitingForLock" : false, "lockStats" : { } } ], "ok" : 1 } MongoDB Enterprise testrs:PRIMARY>