Terminate Running Operations

Overview

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

Available Procedures

maxTimeMS

New in version 2.6.

The maxTimeMS() method sets a time limit for anoperation. 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 atime limit of 30 milliseconds for this query:

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

Terminate a Command

Consider a potentially long running operation usingdistinct to return each distinct collection field thathas a city key:

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

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

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

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

  1. { "n" : 0,
  2.   "connectionId" : 1,
  3.   "err" : "operation exceeded time limit",
  4.   "ok" : 1 }

killOp

The db.killOp() method interrupts a running operation atthe next interrupt point. db.killOp() identifiesthe target operation by operation ID.

  1. db.killOp(<opId>)

Warning

Terminate running operations with extreme caution. Only usedb.killOp() to terminate operations initiated by clientsand do not terminate internal database operations.

Sharded Cluster

Starting in MongoDB 4.0, the killOp command can be run ona mongos and can kill queries (i.e. read operations)that span shards in a cluster. The killOp command from themongos does not propagate to the shards when theoperation 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 amongos, see the localOps parameter in$currentOp.