$currentOp (aggregation)

Definition

$currentOp

Returns a stream of documents containing information on active and/or dormant operations as well as inactive sessions that are holding locks as part of a transaction. The stage returns a document for each operation or session. To run $currentOp, use the db.aggregate() helper on the admin database.

The $currentOp aggregation stage is preferred over the currentOp command and its mongosh helper method db.currentOp(). Because the currentOp command and db.currentOp() helper method return the results in a single document, the total size of the currentOp result set is subject to the maximum 16MB BSON size limit for documents. The $currentOp stage returns a cursor over a stream of documents, each of which reports a single operation. Each operation document is subject to the 16MB BSON limit, but unlike the currentOp command, there is no limit on the overall size of the result set.

$currentOp also enables you to perform arbitrary transformations of the results as the documents pass through the pipeline.

{ $currentOp: { allUsers: <boolean>, idleConnections: <boolean>, idleCursors: <boolean>, idleSessions: <boolean>, localOps: <boolean> } }

{ $currentOp: { } }

Constraints

Examples

The following examples show how to use the $currentOp aggregation stage.

db.getSiblingDB("admin").aggregate( [
   { $currentOp : { allUsers: true, idleSessions: true } },
   { $match : { active: false, transaction : { $exists: true } } }
] )

db.getSiblingDB("admin").aggregate( [
   { $currentOp : { allUsers: true, idleSessions: true } },
   { $match : { type: "idleSession" } }
] )

{
   "type" : "idleSession",
   "host" : "example.mongodb.com:27017",
   "desc" : "inactive transaction",
   "client" : "198.51.100.1:50428",
   "connectionId" : NumberLong(32),
   "appName" : "",
   "clientMetadata" : {
      "driver" : {
         "name" : "PyMongo",
         "version" : "3.9.0"
      },
      "os" : {
         "type" : "Darwin",
         "name" : "Darwin",
         "architecture" : "x86_64",
         "version" : "10.14.5"
      },
      "platform" : "CPython 3.7.1.final.0"
   },
   "lsid" : {
      "id" : UUID("ff21e1a9-a130-4fe0-942f-9e6b6c67ea3c"),
      "uid" : BinData(0,"3pxqkATNUYKV/soT7qqKE0zC0BFb0pBz1pk4xXcSHsI=")
   },
   "transaction" : {
      "parameters" : {
         "txnNumber" : NumberLong(4),
         "autocommit" : false,
         "readConcern" : {
            "level" : "snapshot",
            "afterClusterTime" : Timestamp(1563892246, 1)
         }
      },
      "readTimestamp" : Timestamp(0, 0),
      "startWallClockTime" : "2019-07-23T10:30:49.461-04:00",
      "timeOpenMicros" : NumberLong(1913590),
      "timeActiveMicros" : NumberLong(55),
      "timeInactiveMicros" : NumberLong(1913535),
      "expiryTime" : "2019-07-23T10:31:49.461-04:00"
   },
   "waitingForLock" : false,
   "active" : false,
   "locks" : {
      "ReplicationStateTransition" : "w",
      "Global" : "w",
      "Database" : "w",
      "Collection" : "w"
   },
   "lockStats" : {
      "ReplicationStateTransition" : {
         "acquireCount" : {
            "w" : NumberLong(5)
         }
      },
      "Global" : {
         "acquireCount" : {
            "r" : NumberLong(3),
            "w" : NumberLong(1)
         }
      },
      "Database" : {
         "acquireCount" : {
            "r" : NumberLong(2),
            "w" : NumberLong(1)
         }
      },
      "Collection" : {
         "acquireCount" : {
            "w" : NumberLong(1)
         }
      },
      "Mutex" : {
         "acquireCount" : {
            "r" : NumberLong(3)
         }
      },
      "oplog" : {
         "acquireCount" : {
            "r" : NumberLong(2)
         }
      }
   },
   "waitingForFlowControl" : false,
   "flowControlStats" : {},
}

db.getSiblingDB("admin").aggregate( [
   { $currentOp : { allUsers: true, idleSessions: true, localOps: true } },
   { $match : { type: "idleSession" } }
] );
// or
db.getSiblingDB("admin").aggregate( [
   { $currentOp : { allUsers: true, idleSessions: true, localOps: true } },
   { $match : { active: false, transaction : { $exists: true } } }
] )

{
   "type" : "idleSession",
   "host" : "example.mongodb.com:27017",
   "desc" : "inactive transaction",
   "client" : "198.51.100.1:49618",
   "connectionId" : NumberLong(48),
   "appName" : "",
   "clientMetadata" : {
      "driver" : {
         "name" : "PyMongo",
         "version" : "3.9.0"
      },
      "os" : {
         "type" : "Darwin",
         "name" : "Darwin",
         "architecture" : "x86_64",
         "version" : "10.14.6"
      },
      "platform" : "CPython 3.7.1.final.0",
      "mongos" : {
         "host" : "example.mongodb.com:27017",
         "client" : "198.51.100.1:53268",
         "version" : "4.2.1"
      }
   },
   "lsid" : {
      "id" : UUID("2c9ce111-133e-45b7-a00f-a7871005cae1"),
      "uid" : BinData(0,"3pxqkATNUYKV/soT7qqKE0zC0BFb0pBz1pk4xXcSHsI=")
   },
   "active" : false,
   "transaction" : {
      "parameters" : {
         "txnNumber" : NumberLong(2),
         "autocommit" : false,
         "readConcern" : {
            "level" : "snapshot",
            "afterClusterTime" : Timestamp(1571869019, 2)
         }
      },
      "globalReadTimestamp" : Timestamp(1571869019, 2),
      "startWallClockTime" : "2019-10-23T18:16:59.341-04:00",
      "timeOpenMicros" : NumberLong(169244639),
      "timeActiveMicros" : NumberLong(535),
      "timeInactiveMicros" : NumberLong(169244104),
      "numParticipants" : 2,
      "participants" : [
         {
            "name" : "shardB",
            "coordinator" : true,
            "readOnly" : false
         },
         {
            "name" : "shardA",
            "coordinator" : false,
            "readOnly" : false
         }
      ],
      "numReadOnlyParticipants" : 0,
      "numNonReadOnlyParticipants" : 2
   }
}

{
   "shard" : "shardB",
   "type" : "idleSession",
   "host" : "shardB.mongodb.com:27018",
   "desc" : "inactive transaction",
   "client_s" : "198.51.100.1:53961",
   "connectionId" : NumberLong(63),
   "appName" : "",
   "clientMetadata" : {
      "driver" : {
         "name" : "PyMongo",
         "version" : "3.9.0"
      },
      "os" : {
         "type" : "Darwin",
         "name" : "Darwin",
         "architecture" : "x86_64",
         "version" : "10.14.6"
      },
      "platform" : "CPython 3.7.1.final.0",
      "mongos" : {
         "host" : "example.mongodb.com:27017",
         "client" : "198.51.100.1:53976",
         "version" : "4.2.0"
      }
   },
   "lsid" : {
      "id" : UUID("720d403c-8daf-40bb-b61e-329e20b0493b"),
      "uid" : BinData(0,"3pxqkATNUYKV/soT7qqKE0zC0BFb0pBz1pk4xXcSHsI=")
   },
   "transaction" : {
      "parameters" : {
         "txnNumber" : NumberLong(1),
         "autocommit" : false,
         "readConcern" : {
            "level" : "snapshot"
         }
      },
      "readTimestamp" : Timestamp(0, 0),
      "startWallClockTime" : "2019-10-21T18:31:12.192-04:00",
      "timeOpenMicros" : NumberLong(24137008),
      "timeActiveMicros" : NumberLong(52),
      "timeInactiveMicros" : NumberLong(24136956),
      "expiryTime" : "2019-10-21T18:32:12.192-04:00"
   },
   "waitingForLock" : false,
   "active" : false,
   "locks" : {
      "ReplicationStateTransition" : "w",
      "Global" : "w",
      "Database" : "w",
      "Collection" : "w"
   },
   "lockStats" : {
      "ReplicationStateTransition" : {
         "acquireCount" : {
            "w" : NumberLong(3)
         }
      },
      "Global" : {
         "acquireCount" : {
            "r" : NumberLong(1),
            "w" : NumberLong(1)
         }
      },
      "Database" : {
         "acquireCount" : {
            "r" : NumberLong(1),
            "w" : NumberLong(1)
         }
      },
      "Collection" : {
         "acquireCount" : {
            "r" : NumberLong(1),
            "w" : NumberLong(1)
         }
      },
      "Mutex" : {
         "acquireCount" : {
            "r" : NumberLong(6)
         }
      }
   }
}
{
   "shard" : "shardA",
   "type" : "idleSession",
   ...
}

db.getSiblingDB("admin").aggregate( [
   { $currentOp: { allUsers: true, localOps: true } },
   { $match: { desc: "query analyzer" } }
] )

{
   "desc" : "query analyzer",
   "ns" : "testDb.testColl",
   "collUuid" : UUID("ed9dfb1d-5b7c-4c6b-82e9-b0f537335795"),
   "samplesPerSecond" : 5,
   "startTime" : ISODate("2023-08-08T16:23:22.846Z"),
   "sampledReadsCount" : NumberLong(2),
   "sampledReadsBytes" : NumberLong(346),
   "sampledWritesCount" : NumberLong(3),
   "sampledWritesBytes" : NumberLong(904)
}

{
   "desc" : "query analyzer",
   "ns" : "testDb.testColl",
   "collUuid" : UUID("5130b4df-5966-434f-85f0-f8956b5ca74e"),
   "samplesPerSecond" : 5,
   "startTime" : ISODate("2023-08-08T16:15:07.427Z"),
   "sampledReadsCount" : NumberLong(2),
   "sampledWritesCount" : NumberLong(3)
}

{
   "desc" : "query analyzer",
   "ns" : "testDb.testColl",
   "collUuid" : UUID("5130b4df-5966-434f-85f0-f8956b5ca74e"),
   "startTime" : ISODate("2023-08-08T16:15:07.427Z"),
   "sampledReadsCount" : NumberLong(2),
   "sampledReadsBytes" : NumberLong(346),
   "sampledWritesCount" : NumberLong(3),
   "sampledWritesBytes" : NumberLong(904)
}

Output Fields

Each output document may contain a subset of the following fields, as relevant for the operation:

$currentOp.type

The type of operation. Values are either:

• op

• idleSession

• idleCursor

If the $currentOp.type is op, $currentOp.op provides details on the specific operation.

$currentOp.host

The name of the host against which the operation is run.

$currentOp.shard

The name of the shard where the operation is running.

Only present for sharded clusters.

$currentOp.desc

A description of the operation.

$currentOp.connectionId

An identifier for the connection where the specific operation originated.

$currentOp.client

The IP address (or hostname) and the ephemeral port of the client connection where the operation originates.

For multi-document transactions, $currentOp.client stores information about the most recent client to run an operation inside the transaction.

For standalones and replica sets only

$currentOp.client_s

The IP address (or hostname) and the ephemeral port of the mongos where the operation originates.

For sharded clusters only

$currentOp.clientMetadata

Additional information on the client.

For multi-document transactions, $currentOp.client stores information about the most recent client to run an operation inside the transaction.

$currentOp.appName

The identifier of the client application which ran the operation. Use the appName connection string option to set a custom value for the appName field.

$currentOp.active

A boolean value specifying whether the operation has started. Value is true if the operation has started or false if the operation is idle, such as an idle connection, an inactive session, or an internal thread that is currently idle. An operation can be active even if the operation has yielded to another operation.

$currentOp.twoPhaseCommitCoordinator

Information on either:

• The commit coordination metrics for a transaction whose write operations span multiple shards.

  Commit coordination is handled by a shard, and $currentOp (run either on a mongos or a shard member) returns a shard's coordination information only for transactions the shard is currently coordinating.

  To filter for only the commit coordination metrics:

  db.getSiblingDB("admin").aggregate( [
      { $currentOp: { allUsers: true, idleSessions: true } },
      { $match: { desc: "transaction coordinator" } }
  ] )

• A specific commit coordination operation (i.e. type is op and desc is "TransactionCoordinator") spawned by the transaction coordinator.

Note

• If run with idleSessions: false, $currentOp does not return the $currentOp.twoPhaseCommitCoordinator information in inactive state

• If access control is enabled and allUsers: false, $currentOp does not return $currentOp.twoPhaseCommitCoordinator information.

$currentOp.twoPhaseCommitCoordinator.lsid

The session identifier for the multi-shard transaction.

The combination of the lsid and txnNumber identifies the transaction.

Available for both the commit coordination metrics and for specific coordination operation.

$currentOp.twoPhaseCommitCoordinator.txnNumber

The transaction number for the multi-shard transaction.

The combination of the txnNumber and lsid identifies the transaction.

Available for both the commit coordination metrics and for specific coordination operation.

$currentOp.twoPhaseCommitCoordinator.action

The specific commit coordination operation spawned by the transaction coordinator:

• "sendingPrepare"

• "sendingCommit"

• "sendingAbort"

• "writingParticipantList"

• "writingDecision"

• "deletingCoordinatorDoc"

Only available for specific coordination operation.

$currentOp.twoPhaseCommitCoordinator.startTime

The start date and time of the action.

Only available for specific coordination operation.

$currentOp.twoPhaseCommitCoordinator.numParticipants

Number of shards participating in this commit.

Only available for the commit coordination metrics.

$currentOp.twoPhaseCommitCoordinator.state

The current step/state of the commit coordination process.

Step/stage	Description
inactive	Not actively part of a commit.
writingParticipantList	Writing a local record of the list of shards that are part of this multi-shard transaction.
waitingForVotes	Waiting for the participants to respond with vote to commit or abort.
writingDecision	Writing a local record of the coordinator's decision to commit or abort based on votes.
waitingForDecisionAck	Waiting for participants to acknowledge the coordinator's decision to commit or abort.
deletingCoordinatorDoc	Deleting the local record of commit decision.

Only available for the commit coordination metrics.

See also $currentOp.twoPhaseCommitCoordinator.stepDurations.

$currentOp.twoPhaseCommitCoordinator.commitStartTime

The date and time when the commit started.

Only available for the commit coordination metrics.

$currentOp.twoPhaseCommitCoordinator.hasRecoveredFromFailover

A boolean that indicates whether the commit coordination was restarted due to failover on the shard that is coordinating the commit.

If hasRecoveredFromFailover is true, then the times specified in $currentOp.twoPhaseCommitCoordinator.stepDurations may not be accurate for all steps.

Only available for the commit coordination metrics.

$currentOp.twoPhaseCommitCoordinator.stepDurations

A document that contains the duration, in microseconds, of the completed or in-progress steps/state of the active process as well as the cumulative total duration; for example:

"stepDurations" : {
   "writingParticipantListMicros" : NumberLong(17801),
   "totalCommitDurationMicros" : NumberLong(42488463),
   "waitingForVotesMicros" : NumberLong(30378502),
   "writingDecisionMicros" : NumberLong(15015),
   "waitingForDecisionAcksMicros" : NumberLong(12077145),
   "deletingCoordinatorDocMicros" : NumberLong(6009)
},

If $currentOp.twoPhaseCommitCoordinator.hasRecoveredFromFailover is true, then the times specified in stepDurations may not be accurate for all steps.

For a coordinator in an inactive state, the document is empty:

"stepDurations" : {
}

Only available for the commit coordination metrics.

See $currentOp.twoPhaseCommitCoordinator.state.

$currentOp.twoPhaseCommitCoordinator.decision

A document that contains the commit/abort decision, for example:

• For a commit decision:

  "decision" : {
     "decision" : "commit",
     "commitTimestamp" : Timestamp(1572034669, 3)
  }

• For an abort decision:

  "decision" : {
     "decision" : "abort",
     "abortStatus" : {
        "code" : 282,
        "codeName" : "TransactionCoordinatorReachedAbortDecision",
        "errmsg" : "Transaction exceeded deadline"
     }
  }

Only available for the commit coordination metrics.

$currentOp.twoPhaseCommitCoordinator.deadline

The date and time by which the commit must finish.

Only available for the commit coordination metrics.

$currentOp.currentOpTime

The start time of the operation.

$currentOp.effectiveUsers

An array that contains a document for each user associated with the operation. Each user document contains the user name and the authentication db.

Tip

See also:

$currentOp.runBy

$currentOp.runBy

An array that contains a document for each user who is impersonating the effectiveUser(s) for the operation. The runBy document contains the user name and the authentication db. In general, the impersonating user is the __system user; e.g.

"runBy" : [
   {
      "user" : "__system",
      "db" : "local"
   }
]

$currentOp.opid

The identifier for the operation. You can pass this value to db.killOp() in mongosh to terminate the operation.

Warning

Terminate running operations with extreme caution. Only use db.killOp() to terminate operations initiated by clients and do not terminate internal database operations.

$currentOp.secs_running

The duration of the operation in seconds. MongoDB calculates this value by subtracting the current time from the start time of the operation.

Only present if the operation is running; i.e. if active is true.

$currentOp.microsecs_running

The duration of the operation in microseconds. MongoDB calculates this value by subtracting the current time from the start time of the operation.

Only present if the operation is running; i.e. if active is true.

$currentOp.lsid

The session identifier.

Only present if the operation is associated with a session.

$currentOp.transaction

A document that contains multi-document transaction information.

Only present if the operation is part of a transaction:

• On a replica set.

• On a sharded cluster if $currentOp is run without localOps:true. The transaction information is per shard.

• On a sharded cluster if $currentOp is run with localOps:true. The transaction information is a composite view rather than per shard.

$currentOp.transaction.parameters

A document that contains information on multi-document transaction.

Only present if the operation is part of a multi-document transaction.

$currentOp.transaction.parameters.txnNumber

The transaction number.

Only present if the operation is part of a multi-document transaction.

$currentOp.transaction.parameters.autocommit

A boolean flag that indicates if autocommit is on for the transaction.

Only present if the operation is part of a multi-document transaction.

$currentOp.transaction.parameters.readConcern

The read concern for the transaction.

Multi-document transactions support read concern "snapshot", "local", and "majority".

Only present if the operation is part of a multi-document transaction.

$currentOp.transaction.globalReadTimestamp

The timestamp of the snapshot read by the operations in the sharded cluster transaction that uses "snapshot" read concern. For transactions on sharded clusters, the read concern "snapshot" of the data is synchronized across shards; i.e. other read concerns cannot guarantee that the data is from the same snapshot view across the shards.

Only present when run with localOps: true for sharded cluster transactions.

$currentOp.transaction.readTimestamp

The timestamp of the snapshot being read by the operations in this transaction

Only present if the operation is part of a multi-document transaction. However, the field is not returned if:

• the transaction is on a sharded cluster and uses "snapshot" read concern, and

• $currentOp is run with localOps: true.

Instead, $currentOp.transaction.globalReadTimestamp is returned.

$currentOp.transaction.startWallClockTime

The date and time (with time zone) of the transaction start.

Only present if the operation is part of a multi-document transaction.

$currentOp.transaction.timeOpenMicros

The duration, in microseconds, for the transaction.

The timeActiveMicros value added to the timeInactiveMicros should equal the timeOpenMicros.

Only present if the operation is part of a multi-document transaction.

$currentOp.transaction.timeActiveMicros

The total amount of time that the transaction has been active; i.e. when the transaction had operations running.

The timeActiveMicros value added to the timeInactiveMicros should equal the timeOpenMicros.

Only present if the operation is part of a multi-document transaction.

$currentOp.transaction.timeInactiveMicros

The total amount of time that the transaction has been inactive; i.e. when the transaction had no operations running.

The timeInactiveMicros value added to the timeActiveMicros should equal the timeOpenMicros.

Only present if the operation is part of a multi-document transaction.

$currentOp.transaction.numParticipants

Number of shards participating in this transaction.

Only present if the operation is part of a transaction on a sharded cluster and $currentOp is run with localOps: true

$currentOp.transaction.participants

An array of documents detailing the participating shards in this transaction. Each document contains the name, a flag indicating if the shard acts as the commit coordinator, and a flag indicating if the shard is only involved in read operations for the transaction.

{
   "name" : "shardA",
   "coordinator" : false,
   "readOnly" : false
}

Only present if the operation is part of a transaction on a sharded cluster and $currentOp is run with localOps: true

$currentOp.transaction.numReadOnlyParticipants

Number of shards only affected by read operations in this transaction.

Only present if the operation is part of a transaction on a sharded cluster and $currentOp is run with localOps: true

$currentOp.transaction.numNonReadOnlyParticipants

Number of shards affected by operations other than reads in this transaction.

Only present if the operation is part of a transaction on a sharded cluster and $currentOp is run with localOps: true

$currentOp.transaction.expiryTime

The date and time (with time zone) when the transaction will time out and abort.

The $currentOp.transaction.expiryTime equals the $currentOp.transaction.startWallClockTime + the transactionLifetimeLimitSeconds.

For more information, see Runtime Limit for transactions.

Only present if the operation is part of a multi-document transaction.

$currentOp.op

A string that identifies the specific operation type. Only present if $currentOp.type is op.

The possible values are:

• "none"

• "update"

• "insert"

• "query"

• "command"

• "getmore"

• "remove"

• "killcursors"

"command" operations include most commands such as the createIndexes, aggregate, and findAndModify.

"query" operations include find operations and OP_QUERY operations.

$currentOp.ns

The namespace the operation targets. A namespace consists of the database name and the collection name concatenated with a dot (.); that is, "<database>.<collection>".

$currentOp.command

A document containing the full command object associated with this operation.

For example, the following output contains the command object for a find operation on a collection named items in a database named test:

"command" : {
  "find" : "items",
  "filter" : {
    "sku" : 1403978
  },
  ...
  "$db" : "test"
}

The following example output contains the command object for a getMore operation generated by a command with cursor ID 19234103609 on a collection named items in a database named test:

"command" : {
    "getMore" : NumberLong("19234103609"),
    "collection" : "items",
    "batchSize" : 10,
    ...
    "$db" : "test"
},

If the command document exceeds 1 kilobyte, the document has the following form:

"command" : {
  "$truncated": <string>,
  "comment": <string>
}

The $truncated field contains a string summary of the document excluding the document's comment field if present. If the summary still exceeds 1 kilobyte then it is further truncated, denoted by an ellipsis (...) at the end of the string.

The comment field is present if a comment was passed to the operation. A comment may be attached to any database command.

$currentOp.cursor

A document that contains the cursor information for idleCursor and getmore operations; i.e. where type is idleCursor or op is getmore.

If reporting on a getmore operation before the getmore has accessed its cursor information, the cursor field is not available.

$currentOp.cursor.cursorId

The ID of the cursor.

$currentOp.cursor.createdDate

The date and time when the cursor was created.

$currentOp.cursor.lastAccessDate

The date and time when the cursor was last used.

If the cursor is actively in use (i.e. op is getmore and the type is not idleCursor), then lastAccessDate reports either the time the previous getmore ended or the time the cursor was created if this is the first getmore.

$currentOp.cursor.nDocsReturned

The cumulative number of documents returned by the cursor.

$currentOp.cursor.nBatchesReturned

The cumulative number of batches returned by the cursor.

$currentOp.cursor.noCursorTimeout

The flag that indicates that the cursor doesn't timeout when idle; i.e. if the cursor has the noTimeout option set.

• If true, the cursor does not time out when idle.

• If false, the cursor times out when idle.

Tip

See also:

cursor.addOption()

$currentOp.cursor.tailable

The flag that indicates if the cursor is a tailable cursor for a capped collection. Tailable cursors remain open after the client exhausts the results in the initial cursor.

Tip

See also:

• find

• cursor.tailable()

• cursor.addOption()

$currentOp.cursor.awaitData

The flag that indicates whether the tailable cursor should temporarily block a getMore command on the cursor while waiting for new data rather than returning no data.

For non-tailable cursors, the value is always false.

Tip

See also:

• find

• cursor.tailable()

• cursor.addOption()

$currentOp.cursor.originatingCommand

The originatingCommand field contains the full command object (e.g. find or aggregate) which originally created the cursor.

$currentOp.cursor.planSummary

A string that specifies whether the cursor uses a collection scan (COLLSCAN) or an index scan (IXSCAN { ... }).

The IXSCAN also includes the specification document of the index used.

Not available when running with localOps: true on mongos or when reporting on idleCursors.

$currentOp.cursor.operationUsingCursorId

The opid of the operation using the cursor.

Only present if the cursor is not idle.

$currentOp.cursor.queryFramework

New in version 6.2.

A string that specifies the query framework used to process an operation.

$currentOp.planSummary

A string that specifies whether the cursor uses a collection scan (COLLSCAN) or an index scan (IXSCAN { ... }).

Not available when running with localOps: true on mongos.

$currentOp.prepareReadConflicts

The number of times the current operation had to wait for a prepared transaction with a write to commit or abort.

While waiting, the operation continues to hold any necessary locks and storage engine resources.

$currentOp.writeConflicts

The number of times the current operation conflicted with another write operation on the same document.

$currentOp.numYields

numYields is a counter that reports the number of times the operation has yielded to allow other operations to complete.

Typically, operations yield when they need access to data that MongoDB has not yet fully read into memory. This allows other operations that have data in memory to complete quickly while MongoDB reads in data for the yielding operation.

$currentOp.dataThroughputLastSecond

Amount of data (in MiB) processed by the validate operation in the last second. Only available for a validate operation that is currently scanning documents. For example:

"msg" : "Validate: scanning documents Validate: scanning documents: 7258/24000 30%",
"progress" : {
   "done" : 7258,
   "total" : 24000
},
"numYields" : 0,
"dataThroughputLastSecond" : 15.576952934265137,
"dataThroughputAverage" : 15.375944137573242,

$currentOp.dataThroughputAverage

The average amount of data (in MiB) processed by the validate operation. Only available for a validate operation that is currently scanning documents. For example:

"msg" : "Validate: scanning documents Validate: scanning documents: 7258/24000 30%",
"progress" : {
   "done" : 7258,
   "total" : 24000
},
"numYields" : 0,
"dataThroughputLastSecond" : 15.576952934265137,
"dataThroughputAverage" : 15.375944137573242,

$currentOp.waitingForLatch

The waitingForLatch document is only available if the operation is waiting to acquire an internal locking primitive (a.k.a. a latch) or for an internal condition to be met.

For example,

"waitingForLatch" : {
   "timestamp" : ISODate("2020-03-19T23:25:58.412Z"),
   "captureName" : "FutureResolution",
   "backtrace" : [ ]   // Only if backtrace: true
},

Output Field	Description
timestamp	The date and time at which the operation started to wait.
captureName	The internal name of the section where the operation is currently blocked.
backtrace	The callstack, if available. The field is only included if backtrace: true.

$currentOp.locks

The locks document reports the type and mode of locks the operation currently holds. The possible lock types are as follows:

Lock Type	Description
ParallelBatchWriterMode	Represents a lock for parallel batch writer mode. In earlier versions, PBWM information was reported as part of the Global lock information.
ReplicationStateTransition	Represents lock taken for replica set member state transitions.
Global	Represents global lock.
Database	Represents database lock.
Collection	Represents collection lock.
Mutex	Represents mutex.
Metadata	Represents metadata lock.
oplog	Represents lock on the oplog.

The possible modes are as follows:

Lock Mode	Description
R	Represents Shared (S) lock.
W	Represents Exclusive (X) lock.
r	Represents Intent Shared (IS) lock.
w	Represents Intent Exclusive (IX) lock.

$currentOp.lockStats

For each lock type and mode (see locks for descriptions of lock types and modes), returns the following information:

$currentOp.lockStats.acquireCount

Number of times the operation acquired the lock in the specified mode.

$currentOp.lockStats.acquireWaitCount

Number of times the operation had to wait for the acquireCount lock acquisitions because the locks were held in a conflicting mode. acquireWaitCount is less than or equal to acquireCount.

$currentOp.lockStats.timeAcquiringMicros

Cumulative time in microseconds that the operation had to wait to acquire the locks.

timeAcquiringMicros divided by acquireWaitCount gives an approximate average wait time for the particular lock mode.

$currentOp.lockStats.deadlockCount

Number of times the operation encountered deadlocks while waiting for lock acquisitions.

$currentOp.waitingForLock

Returns a boolean value. waitingForLock is true if the operation is waiting for a lock and false if the operation has the required lock.

$currentOp.msg

The msg provides a message that describes the status and progress of the operation. In the case of indexing or mapReduce operations, the field reports the completion percentage.

$currentOp.progress

Reports on the progress of mapReduce or indexing operations. The progress fields corresponds to the completion percentage in the msg field. The progress specifies the following information:

$currentOp.progress.done

Reports the number of work items completed.

$currentOp.progress.total

Reports the total number of work items.

$currentOp.killPending

Returns true if the operation is currently flagged for termination. When the operation encounters its next safe termination point, the operation terminates.

$currentOp.waitingForFlowControl

A boolean that indicates if the operation had to wait because of flow control.

$currentOp.flowControlStats

The flow control statistics for this operation.

$currentOp.flowControlStats.acquireCount

The number of times this operation acquired a ticket.

$currentOp.flowControlStats.acquireWaitCount

The number of times this operation waited to acquire a ticket.

$currentOp.flowControlStats.timeAcquiringMicros

The total time this operation has waited to acquire a ticket.

$currentOp.totalOperationTimeElapsed

The total time elapsed, in seconds, for the current resharding operation. The time is set to 0 when a new resharding operation starts.

Only present if a resharding operation is taking place.

New in version 5.0.

$currentOp.remainingOperationTimeEstimated

The estimated time remaining in seconds for the current resharding operation. The time is set to -1 when a new resharding operation starts.

Only present when a resharding operation is taking place. This field may not be present if an estimate cannot not be computed.

New in version 5.0.

$currentOp.approxDocumentsToCopy

The approximate number of documents to be copied from the donor shards to the recipient shards during the resharding operation. This number is an estimate that is set at the beginning of the resharding operation and does not change after it has been set. The number is set to 0 when a new resharding operation starts. It is possible for $currentOp.documentsCopied and $currentOp.bytesCopied to end up exceeding $currentOp.approxDocumentsToCopy and $currentOp.approxBytesToCopy, respectively, if the post-resharding data distribution is not perfectly uniform.

Only present on a recipient shard when a resharding operation is taking place.

New in version 5.0.

$currentOp.documentsCopied

The number of documents copied form donor shards to recipient shards during the resharding operation. The number is set to 0 when a new resharding operation starts.

Only present on a recipient shard when a resharding operation is taking place.

New in version 5.0.

$currentOp.approxBytesToCopy

The approximate number of bytes to be copied from the donor shards to the recipient shards during the resharding operation. This number is an estimate that is set at the beginning of the resharding operation and does not change after it has been set. The number is set to 0 when a new resharding operation starts. It is possible for $currentOp.documentsCopied and $currentOp.bytesCopied to end up exceeding $currentOp.approxDocumentsToCopy and $currentOp.approxBytesToCopy, respectively, if the post-resharding data distribution is not perfectly uniform.

Only present on a recipient shard when a resharding operation is taking place.

New in version 5.0.

$currentOp.bytesCopied

The number of bytes copied from donor shards to recipient shards during the resharding operation. The number is set to 0 when a new resharding operation starts.

Only present on a recipient shard when a resharding operation is taking place.

New in version 5.0.

$currentOp.totalCopyTimeElapsed

The total elapsed time, in seconds, for ongoing data copy tasks from donor shards to recipient shards for the current resharding operation. The time is set to 0 when a new resharding operation starts.

Only present on a recipient shard when a resharding operation is taking place.

New in version 5.0.

$currentOp.oplogEntriesFetched

The number of entries fetched from the oplog for the current resharding operation. The number is set to 0 when a new resharding operation starts.

Only present on a recipient shard when a resharding operation is taking place.

New in version 5.0.

$currentOp.oplogEntriesApplied

The number of entries applied to the oplog for the current resharding operation. The number is set to 0 when a new resharding operation starts.

Only present on a recipient shard when a resharding operation is taking place.

New in version 5.0.

$currentOp.totalApplyTimeElapsed

The total elapsed time, in seconds, for the apply step of the current resharding operation. In the apply step, recipient shards apply oplog entries to modify their data based on new incoming writes from donor shards. The time is set to 0 when a new resharding operation starts.

Only present on a recipient shard when a resharding operation is taking place.

New in version 5.0.

$currentOp.countWritesDuringCriticalSection

The number of writes performed in the critical section for the current resharding operation. The critical section prevents new incoming writes to the collection currently being resharded. The number is set to 0 when a new resharding operation starts.

Only present on a donor shard when a resharding operation is taking place.

New in version 5.0.

$currentOp.totalCriticalSectionTimeElapsed

The total elapsed time, in seconds, for the critical section of the current resharding operation. The critical section prevents new incoming writes to the collection currently being resharded. The time is set to 0 when a new resharding operation starts.

Only present on a donor shard when a resharding operation is taking place.

New in version 5.0.

$currentOp.donorState

The current state of a donor shard for the resharding operation. The state is set to unused when a new resharding operation starts.

Only present on a donor shard when a resharding operation is taking place.

State	Description
unused	The resharding operation is about to start or recovering from a primary failover.
preparing-to-donate	The donor shard is preparing to donate data to the recipient shards.
donating-initial-data	The donor shard is donating data to the recipient shards.
donating-oplog-entries	The donor shard is donating oplog entries to the recipient shards.
preparing-to-block-writes	The donor shard is about to prevent new incoming write operations to the collection that is being resharded.
error	An error occurred during the resharding operation.
blocking-writes	The donor shard is preventing new incoming write operations and the donor shard has notified all recipient shards that new incoming writes are prevented.
done	The donor shard has dropped the old sharded collection and the resharding operation is complete.

New in version 5.0.

$currentOp.recipientState

The current state of a recipient shard for a resharding operation. The state is set to unused when a new resharding operation starts.

Only present on a donor shard when a resharding operation is taking place.

State	Description
unused	The resharding operation is about to start or recovering from a primary failover.
awaiting-fetch-timestamp	The recipient shard is waiting for the donor shards to be prepared to donate their data.
creating-collection	The recipient shard is creating the new sharded collection.
cloning	The recipient shard is receiving data from the donor shards.
applying	The recipient shard is applying oplog entries to modify its copy of the data based on the new incoming writes from donor shards.
error	An error occurred during the resharding operation.
strict-consistency	The recipient shard has all data changes stored in a temporary collection.
done	The resharding operation is complete.

New in version 5.0.

$currentOp.coordinatorState

The state of the resharding coordinator for the current resharding operation. The resharding coordinator is an operation that runs on the config server primary. The state is set to unused when a new resharding operation starts.

Only present on the coordinating config server.

State	Description
unused	The resharding operation is about to start or recovering from a primary failover.
initializing	The resharding coordinator has inserted the coordinator document into config.reshardingOperations and has added the reshardingFields to the config.collections entry for the original collection.
preparing-to-donate	The resharding coordinator has created a config.collections entry for the temporary resharding collection. has inserted entries into config.chunks for ranges based on the new shard key. has inserted entries into config.tags for any zones associated with the new shard key. The coordinator informs participant shards to begin the resharding operation. The coordinator then waits until all donor shards have picked a minFetchTimestamp and are ready to donate.
cloning	The resharding coordinator informs donor shards to donate data to recipient shards. The coordinator waits for all recipients to finish cloning the data from the donor.
applying	The resharding coordinator informs recipient shards to modify their copies of data based on new incoming writes from donor shards. The coordinator waits for all recipients to finish applying oplog entries.
blocking-writes	The resharding coordinator informs donor shards to prevent new incoming write operations to the collection being resharded. The coordinator then waits for all recipients to have all data changes.
aborting	An unrecoverable error occurred during the resharding operation or the abortReshardCollection command (or the sh.abortReshardCollection() method) was run.
committing	The resharding coordinator removes the config.collections entry for the temporary resharding collection. The coordinator then adds the recipientFields to the source collection's entry.

New in version 5.0.

$currentOp.opStatus

The current state of a resharding operation.

Only present if a resharding operation is taking place. Once the operation has completed, the operation is removed from currentOp output.

State	Description
actively running	The resharding operation is actively running.
success	The resharding operation has succeeded.
failure	The resharding operation has failed.
canceled	The resharding operation was canceled.

New in version 5.0.

$currentOp.collUuid

The UUID of the sampled collection.

This field only appears on documents related to query sampling. For details, see Sampled Queries.

New in version 7.0.

$currentOp.startTime

The time at which query sampling began.

This field only appears on documents related to query sampling. For details, see Sampled Queries.

New in version 7.0.

$currentOp.samplesPerSecond

The maximum number of queries to sample per second.

Only reported when running $currentOp on mongos.

This field only appears on documents related to query sampling. For details, see Sampled Queries.

New in version 7.0.

$currentOp.sampledReadsCount

The number of sampled read queries.

This field only appears on documents related to query sampling. For details, see Sampled Queries.

New in version 7.0.

$currentOp.sampledWritesCount

The number of sampled write queries.

This field only appears on documents related to query sampling. For details, see Sampled Queries.

New in version 7.0.

$currentOp.sampledReadsBytes

The size of the sampled read queries, in bytes.

On a replica set, this is reported on every mongod.

On a sharded cluster, this only reported on mongod with --shardsvr.

This field only appears on documents related to query sampling. For details, see Sampled Queries.

New in version 7.0.

$currentOp.sampledWritesBytes

The size of the sampled write queries, in bytes.

On a replica set, this is reported on every mongod.

On a sharded cluster, this only reported on mongod with --shardsvr.

This field only appears on documents related to query sampling. For details, see Sampled Queries.

New in version 7.0.