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$currentOp (aggregation)

Definition

New in version 3.6.

$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 mongo shell helper db.currentOp(). Because currentOp command and db.currentOp() helper returns 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 takes an options document as its operand:

Changed in version 4.2.

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

Boolean. If set to false, $currentOp will only report on operations/idle connections/idle cursors/idle sessions belonging to the user who ran the command. If set to true, $currentOp will report operations belonging to all users.

Note

For standalone and replica sets that enforce access control, inprog privilege is required if allUsers: true.

For sharded clusters that enforce access control, the inprog privilege is required to run $currentOp.

Defaults to false.

idleConnections

Boolean. If set to false, $currentOp will only report active operations. If set to true, all operations including idle connections will be returned.

Defaults to false.

idleCursors

Boolean.

If set to true, $currentOp will report on cursors that are “idle”; i.e. open but not currently active in a getMore operation.

Information on idle cursors have the type set to "idleCursor".

Information on cursors currently active in a getMore operation information have the type set to "op" and op set to getmore.

Defaults to false.

New in version 4.2.

idleSessions

Boolean. If set to true, then in addition to reporting on the active/dormant operations, $currentOp returns information on inactive sessions that are holding locks as part of a transaction. Each inactive session will appear as a separate document in the $currentOp stream.

The document for a session includes information on the session id in the lsid field and the transaction in the transaction field.

Starting in MongoDB 4.2, information on idle sessions have the type set to "idleSession".

If set to false, $currentOp will not report on inactive sessions.

Defaults to true.

New in version 4.0.

localOps

Boolean. If set to true for an aggregation running on mongos, $currentOp reports only those operations running locally on that mongos. If false, then the $currentOp will instead report operations running on the shards.

The localOps parameter has no effect for $currentOp aggregations running on mongod.

Defaults to false.

New in version 4.0.

Omitting any of the above parameters will cause $currentOp to use that parameter’s default value. Specify an empty document, as shown below, to use the default values of all parameters.

{ $currentOp: { } }

Constraints

  • $currentOp must be the first stage in the pipeline.
  • Pipelines that start with $currentOp can only be run on the admin database.
  • On a standalone or replica set with authentication enabled, the inprog privilege is required to run $currentOp if the allUsers parameter is set to true.
  • On a sharded cluster, the inprog privilege is required to run all $currentOp pipelines.
  • $currentOp is not allowed in transactions.

Example

The following example returns information on inactive sessions that are holding locks as part of a transaction. Specifically:

  • The first stage returns documents for all active operations as well as inactive sessions that are holding locks as part of a transaction.
  • The second stage filters for just those documents related to inactive sessions that are holding locks as part of a transaction.

Tip

For standalone and replica sets that enforce access control, inprog privilege is required if allUsers: true.

For sharded clusters that enforce access control, the inprog privilege is required to run $currentOp.

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

Starting in version 4.2, you can use $currentOp.type to specify an equivalent filter:

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

Both operations return documents of the form:

{
   "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" : "2019-07-23T10:30:49.461-0400",
      "timeOpenMicros" : NumberLong(1913590),
      "timeActiveMicros" : NumberLong(55),
      "timeInactiveMicros" : NumberLong(1913535),
      "expiryTime" : "2019-07-23T10:31:49.461-0400"
   },
   "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" : {
    }

}

Output Fields

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

$currentOp.type

New in version 4.2.

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

New in version 3.4.

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.currentOpTime

The start time of the operation.

New in version 3.6.

$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.

See also

$currentOp.runBy

New in version 4.2.

$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"
   }
]

New in version 4.2.

$currentOp.opid

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

New in version 3.6.

$currentOp.transaction

A document that contains multi-document transaction information.

Only present if the operation is part of a transaction.

New in version 4.0.

$currentOp.transaction.parameters

A document that contains information on multi-document transaction.

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

New in version 4.0.

$currentOp.transaction.parameters.txnNumber

The transaction number.

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

New in version 4.0.

$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.

New in version 4.0.2.

$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.

New in version 4.0.2.

$currentOp.transaction.readTimestamp

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

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

New in version 4.0.2.

$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.

New in version 4.0.2.

$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.

New in version 4.0.2.

$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.

New in version 4.0.2.

$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.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, seee Runtime Limit for transactions.

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

New in version 4.0.2.

$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

Changed in version 3.6.

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.

$currentOp.cursor

New in version 4.2.

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

New in version 4.2.

The id of the cursor.

$currentOp.cursor.createdDate

New in version 4.2.

The date and time when the cursor was created.

$currentOp.cursor.lastAccessDate

New in version 4.2.

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

New in version 4.2.

The cumulative number of documents returned by the cursor.

$currentOp.cursor.nBatchesReturned

New in version 4.2.

The curmulative number of batches returned by the cursor.

$currentOp.cursor.noCursorTimeout

New in version 4.2.

The flag that indicates that the cursor will not 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 will time out when idle.
$currentOp.cursor.tailable

New in version 4.2.

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.

$currentOp.cursor.awaitData

New in version 4.2.

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.

$currentOp.cursor.originatingCommand

New in version 4.2.

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

Note

Starting in version 4.2, MongoDB now returns originatingCommand field as a nested field in the new cursor field. In previous versions, the originatingCommand was a top-level field for the associated "getmore" document.

$currentOp.cursor.planSummary

New in version 4.2.

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

New in version 4.2.

The opid of the operation using the cursor.

Only present if the cursor is not idle.

$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.

New in version 4.2.

$currentOp.writeConflicts

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

New in version 4.2.

$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.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.

New in version 4.2.

ReplicationStateTransition

Represents lock taken for replica set member state transitions.

New in version 4.2.

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 will terminate.

$currentOp.waitingForFlowControl

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

New in version 4.2.

$currentOp.flowControlStats

The flow control statistics for this operation.

New in version 4.2.

$currentOp.flowControlStats.acquireCount

The number of times this operation acquired a ticket.

New in version 4.2.

$currentOp.flowControlStats.acquireWaitCount

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

New in version 4.2.

$currentOp.flowControlStats.timeAcquiringMicros

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

New in version 4.2.