why global lock(timeAcquiringMicros) is large, there is no pressure in my mongo service(I/O is low, and have many free memory, and command query is low)

     

    slow log as following:

2019-01-09T18:48:12.300+0800 I COMMAND [conn707992] command liangjian.Driver command: find { find: "Driver", filter: { pos:

{ $near: [ 121.5943918185764, 29.84648735894097 ], $maxDistance: 0.02700683945284377 }

, uptime: { $gte: new Date(1547030592051) }, status: 1, btype: { $bitsAnySet: 7 } }, limit: 10, shardVersion: [ Timestamp(0, 0), ObjectId('000000000000000000000000') ], $readPreference: { mode: "secondaryPreferred" }, $clusterTime: { clusterTime: Timestamp(1547030892, 231), signature:

{ hash: BinData(0, 35C6E6D602FDFE11307659B12361C9C11B6AB206), keyId: 6639872680583495699 }

}, $client: { driver:

{ name: "mongo-java-driver", version: "3.4.0" }

, os: { type: "Linux", name: "Linux", architecture: "amd64", version: "2.6.32-642.6.2.el6.toav3.x86_64" }, platform: "Java/Oracle Corporation/1.7.0_79-mockbuild_2015_07_24_09_26-b00", mongos: { host: "fd-mongos-p01.gz01:27024", client: "100.69.94.23:46954", version: "3.6.3" } }, $configServerState: { opTime:

{ ts: Timestamp(1547030887, 374), t: 2 }

}, $db: "liangjian" } planSummary: GEO_NEAR_2D { pos: "2d" } keysExamined:131 docsExamined:146 cursorExhausted:1 numYields:1 nreturned:10 reslen:1525 locks:{ Global: { acquireCount:

{ r: 4 }

, acquireWaitCount: { r: 2 }, timeAcquiringMicros: { r: 243547 } }, Database: { acquireCount:

{ r: 2 }

}, Collection: { acquireCount:

{ r: 2 }

} } protocol:op_msg 247ms

    

 

    system.profile as following:

lbs2_1:SECONDARY> db.system.profile.findOne()
{
"op" : "query",
"ns" : "liangjian.Driver",
"command" : {
"find" : "Driver",
"filter" :

{ "city" : 420100, "_id" : NumberLong("2817439193438706") }

,
"shardVersion" : [
Timestamp(0, 0),
ObjectId("000000000000000000000000")
],
"$readPreference" :

{ "mode" : "secondaryPreferred" }

,
"$clusterTime" : {
"clusterTime" : Timestamp(1547033350, 368),
"signature" :

{ "hash" : BinData(0,"3M+JVUPxF98AftZMDEvZHL1OUnw="), "keyId" : NumberLong("6639871413568143379") }

},
"$client" : {
"driver" :

{ "name" : "mongo-java-driver", "version" : "3.4.0" }

,
"os" :

{ "type" : "Linux", "name" : "Linux", "architecture" : "amd64", "version" : "2.6.32-573.18.1.el6.toa.x86_64" }

,
"platform" : "Java/Oracle Corporation/1.7.0_75-b13",
"mongos" :

{ "host" : "fd-mongos-p02.gz01:27023", "client" : "100.69.96.50:37941", "version" : "3.6.3" }

},
"$configServerState" : {
"opTime" :

{ "ts" : Timestamp(1547033345, 579), "t" : NumberLong(2) }

},
"$db" : "liangjian"
},
"keysExamined" : 1,
"docsExamined" : 1,
"cursorExhausted" : true,
"numYield" : 0,
"locks" : {
"Global" : {
"acquireCount" :

{ "r" : NumberLong(2) }

,
"acquireWaitCount" :

{ "r" : NumberLong(1) }

,
"timeAcquiringMicros" :

{ "r" : NumberLong(324445) }

},
"Database" : {
"acquireCount" :

{ "r" : NumberLong(1) }

},
"Collection" : {
"acquireCount" :

{ "r" : NumberLong(1) }

}
},
"nreturned" : 1,
"responseLength" : 454,
"protocol" : "op_msg",
"millis" : 335,
"planSummary" : "IXSCAN { _id: 1 }",
"execStats" : {
"stage" : "FETCH",
"filter" : {
"city" :

{ "$eq" : 420100 }

},
"nReturned" : 1,
"executionTimeMillisEstimate" : 0,
"works" : 2,
"advanced" : 1,
"needTime" : 0,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"docsExamined" : 1,
"alreadyHasObj" : 0,
"inputStage" : {
"stage" : "IXSCAN",
"nReturned" : 1,
"executionTimeMillisEstimate" : 0,
"works" : 2,
"advanced" : 1,
"needTime" : 0,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"invalidates" : 0,
"keyPattern" :

{ "_id" : 1 }

,
"indexName" : "id",
"isMultiKey" : false,
"multiKeyPaths" :

{ "_id" : [ ] }

,
"isUnique" : true,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 2,
"direction" : "forward",
"indexBounds" :

{ "_id" : [ "[2817439193438706, 2817439193438706]" ] }

,
"keysExamined" : 1,
"seeks" : 1,
"dupsTested" : 0,
"dupsDropped" : 0,
"seenInvalidated" : 0
}
},
"ts" : ISODate("2019-01-09T11:29:10.368Z"),
"client" : "100.69.186.20",
"allUsers" : [

{ "user" : "__system", "db" : "local" }

],
"user" : "__system@local"

 

   The problem doesn't come up very often, it comes up once in a while，who can help me, thanks!