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Terminate Running Operations

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Overview

MongoDB provides two facilitates to terminate running operations: maxTimeMS() and db.killOp(). Use these operations as needed to control the behavior of operations in a MongoDB deployment.

Available Procedures

maxTimeMS

The maxTimeMS() method sets a time limit for an operation. When the operation reaches the specified time limit, MongoDB interrupts the operation at the next interrupt point.

Terminate a Query

From the mongo shell, use the following method to set a time limit of 30 milliseconds for this query:

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db.location.find( { "town": { "$regex": "(Pine Lumber)",
                              "$options": 'i' } } ).maxTimeMS(30)

Terminate a Command

Consider a potentially long running operation using distinct to return each distinct collection field that has a city key:

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db.runCommand( { distinct: "collection",
                 key: "city" } )

You can add the maxTimeMS field to the command document to set a time limit of 45 milliseconds for the operation:

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db.runCommand( { distinct: "collection",
                 key: "city",
                 maxTimeMS: 45 } )

db.getLastError() and db.getLastErrorObj() will return errors for interrupted options:

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{ "n" : 0,
  "connectionId" : 1,
  "err" : "operation exceeded time limit",
  "ok" : 1 }

killOp

The db.killOp() method interrupts a running operation at the next interrupt point. db.killOp() identifies the target operation by operation ID.

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db.killOp(<opId>)

Warning

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

Sharded Cluster

Starting in MongoDB 4.0, the killOp command can be run on a mongos and can kill queries (i.e. read operations) that span shards in a cluster. The killOp command from the mongos does not propagate to the shards when the operation to be killed is a write operation.

For more information on killing operations on a sharded cluster, see:

For information on how to list sharding operations that are active on a mongos, see the localOps parameter in $currentOp.

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