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Diagnostics

lockInfo

On this page

  • Definition
  • Compatibility
  • Syntax
  • Output Example
  • Output Fields

Definition

lockInfo

Returns information on locks that are currently being held or pending. lockInfo is an internal command available on mongod instances only.

Compatibility

This command is available in deployments hosted in the following environments:

  • MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

Important

This command is not supported in M0, M2, and M5 clusters. For more information, see Unsupported Commands.

Syntax

To run, issue the command against the admin database:

db.adminCommand( { lockInfo: 1 } )

Output Example

The following is an example of the output from the lockInfo:

{
   "lockInfo" : [
      {
         "resourceId" : "{2305843009213693953: ParallelBatchWriterMode, 1}",
         "granted" : [
            {
               "mode" : "IS",
               "convertMode" : "NONE",
               "enqueueAtFront" : false,
               "compatibleFirst" : false,
               "debugInfo" : "{ findandmodify: \"hugeindex\", query: { _id: 585.0 }, update: { $pop: { a: 1.0 } }, upsert: false, new: false, lsid: { id: UUID(\"dc611138-04c6-49b1-a7ac-161040dd9d65\") }, $db: \"test\" }",
               "clientInfo" : {
                  "desc" : "conn3",
                  "connectionId" : 3,
                  "client" : "127.0.0.1:55165",
                  "opid" : 28770
               }
            }
         ],
         "pending" : [ ]
      },
      {
         "resourceId" : "{6917529027641081857: Global, 1}",
         "granted" : [
            {
               "mode" : "IX",
               "convertMode" : "NONE",
               "enqueueAtFront" : false,
               "compatibleFirst" : false,
               "debugInfo" : "{ findandmodify: \"hugeindex\", query: { _id: 585.0 }, update: { $pop: { a: 1.0 } }, upsert: false, new: false, lsid: { id: UUID(\"dc611138-04c6-49b1-a7ac-161040dd9d65\") }, $db: \"test\" }",
               "clientInfo" : {
                  "desc" : "conn3",
                  "connectionId" : 3,
                  "client" : "127.0.0.1:55165",
                  "opid" : 28770
               }
            },
            {
               "mode" : "IX",
               "convertMode" : "NONE",
               "enqueueAtFront" : false,
               "compatibleFirst" : false,
               "debugInfo" : "index build: 29d48366-63ad-41e2-a689-69255a89c094",
               "clientInfo" : {
                  "desc" : "IndexBuildsCoordinatorMongod-0",
                  "opid" : 27437
               }
            }
         ],
         "pending" : [ ]
      },
      {
         "resourceId" : "{4611686018427387905: ReplicationStateTransition, 1}",
         "granted" : [
            {
               "mode" : "IX",
               "convertMode" : "NONE",
               "enqueueAtFront" : false,
               "compatibleFirst" : false,
               "debugInfo" : "{ findandmodify: \"hugeindex\", query: { _id: 585.0 }, update: { $pop: { a: 1.0 } }, upsert: false, new: false, lsid: { id: UUID(\"dc611138-04c6-49b1-a7ac-161040dd9d65\") }, $db: \"test\" }",
               "clientInfo" : {
                  "desc" : "conn3",
                  "connectionId" : 3,
                  "client" : "127.0.0.1:55165",
                  "opid" : 28770
               }
            },
            {
               "mode" : "IX",
               "convertMode" : "NONE",
               "enqueueAtFront" : false,
               "compatibleFirst" : false,
               "debugInfo" : "index build: 29d48366-63ad-41e2-a689-69255a89c094",
               "clientInfo" : {
                  "desc" : "IndexBuildsCoordinatorMongod-0",
                  "opid" : 27437
               }
            }
         ],
         "pending" : [ ]
      },
      {
         "resourceId" : "{10123292395995783581: Database, 899920359141007773, test}",
         "granted" : [
            {
               "mode" : "IX",
               "convertMode" : "NONE",
               "enqueueAtFront" : false,
               "compatibleFirst" : false,
               "debugInfo" : "{ findandmodify: \"hugeindex\", query: { _id: 585.0 }, update: { $pop: { a: 1.0 } }, upsert: false, new: false, lsid: { id: UUID(\"dc611138-04c6-49b1-a7ac-161040dd9d65\") }, $db: \"test\" }",
               "clientInfo" : {
                  "desc" : "conn3",
                  "connectionId" : 3,
                  "client" : "127.0.0.1:55165",
                  "opid" : 28770
               }
            },
            {
               "mode" : "IX",
               "convertMode" : "NONE",
               "enqueueAtFront" : false,
               "compatibleFirst" : false,
               "debugInfo" : "index build: 29d48366-63ad-41e2-a689-69255a89c094",
               "clientInfo" : {
                  "desc" : "IndexBuildsCoordinatorMongod-0",
                  "opid" : 27437
               }
            }
         ],
         "pending" : [ ]
      },
      {
         "resourceId" : "{12576221391967629173: Collection, 1047006345899159413, test.hugeindex}",
         "granted" : [
            {
               "mode" : "IX",
               "convertMode" : "NONE",
               "enqueueAtFront" : false,
               "compatibleFirst" : false,
               "debugInfo" : "{ findandmodify: \"hugeindex\", query: { _id: 585.0 }, update: { $pop: { a: 1.0 } }, upsert: false, new: false, lsid: { id: UUID(\"dc611138-04c6-49b1-a7ac-161040dd9d65\") }, $db: \"test\" }",
               "clientInfo" : {
                  "desc" : "conn3",
                  "connectionId" : 3,
                  "client" : "127.0.0.1:55165",
                  "opid" : 28770
               }
            },
            {
               "mode" : "IX",
               "convertMode" : "NONE",
               "enqueueAtFront" : false,
               "compatibleFirst" : false,
               "debugInfo" : "index build: 29d48366-63ad-41e2-a689-69255a89c094",
               "clientInfo" : {
                  "desc" : "IndexBuildsCoordinatorMongod-0",
                  "opid" : 27437
               }
            }
         ],
         "pending" : [ ]
      }
   ],
   "ok" : 1
}

Output Fields

lockInfo

An array of documents that report on the lock information. Each document includes:

lockInfo.resourceId

The resource on which the locks are being held or pending.

lockInfo.granted

An array of documents. Each document provides information on locks that are currently granted on the resource.

lockInfo.pending

An array of documents. Each document provides information on locks that are currently pending on the resource.

Lock Information

For each granted or pending lock document, information include:

Field
Description
mode

Specifies the lock mode:

Lock Mode
Description
S
Shared
X
Exclusive
IS
Intent Shared
IX
Intent Exclusive (IX)
convertMode
Specifies the new lock mode for conversion.
enqueueAtFront
A boolean that indicates whether to put the lock at the front of the queue or the back in case of conflict.
compatibleFirst
A boolean that indicates to grant lock requests based on compatibility with already granted locks or to use the first-in-first-out (FIFO) order.
debugInfo
Information about the operation that issued the lock request.
clientInfo
A document detailing the client information.

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