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Diagnostics

connPoolStats

On this page

  • Definition
  • Compatibility
  • Syntax
  • Behavior
  • Example
  • Output

Definition

connPoolStats

The command connPoolStats returns information regarding the open outgoing connections from the current database instance to other members of the sharded cluster or replica set.

To run connPoolStats, use the db.runCommand( { <command> } ) method.

Note

connPoolStats only returns meaningful results for mongos instances and for mongod instances in sharded clusters.

Compatibility

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

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

Note

This command is supported in all MongoDB Atlas clusters. For information on Atlas support for all commands, see Unsupported Commands.

Syntax

The command has the following syntax:

db.runCommand( { "connPoolStats" : 1 } )

The value of the argument (i.e. 1 ) does not affect the output of the command.

Behavior

connPoolStats includes aggregated statistics in its output:

  • The hosts field displays the information aggregated by host.

  • The pools field displays the information aggregated by pool.

Note

To avoid interference with any running operations, connPoolStats does not take any locks. As such, the counts may change slightly as connPoolStats gathers information, resulting in slight differences between the hosts and pools connection counts.

Example

The following operation uses the db.runCommand() method to run the connPoolStats command on a mongos of a sharded cluster. The sharded cluster has 2 shards, each a single-member replica set, and a config server replica set. The mongos runs on a 4-core machine.

db.runCommand( { "connPoolStats" : 1 } )

The command returns the output of the following form:

Note

The connPoolStats output varies depending on the deployment and the member against which you run connPoolStats among other factors.

{
   "numClientConnections" : <num>,
   "numAScopedConnections" : <num>,
   "totalInUse" : <num>,
   "totalAvailable" : <num>,
   "totalCreated" : <num>,
   "totalRefreshing" : <num>,
   "replicaSetMatchingStrategy" : <string>,
   "pools" : {
      "NetworkInterfaceTL-TaskExecutorPool-0" : {
         "poolInUse" : <num>,
         "poolAvailable" : <num>,
         "poolCreated" : <num>,
         "poolRefreshing" : <num>,
         "cfg1.example.net:27019" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         }
      },
      "NetworkInterfaceTL-TaskExecutorPool-1" : {
         "poolInUse" : <num>,
         "poolAvailable" : <num>,
         "poolCreated" : <num>,
         "poolRefreshing" : <num>,
         "cfg1.example.net:27019" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         }
      },
      "NetworkInterfaceTL-TaskExecutorPool-2" : {
         "poolInUse" : <num>,
         "poolAvailable" : <num>,
         "poolCreated" : <num>,
         "poolRefreshing" : <num>,
         "cfg1.example.net:27019" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         }
      },
      "NetworkInterfaceTL-TaskExecutorPool-3" : {
         "poolInUse" : <num>,
         "poolAvailable" : <num>,
         "poolCreated" : <num>,
         "poolRefreshing" : <num>,
         "cfg1.example.net:27019" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         }
      },
      "NetworkInterfaceTL-ShardRegistry" : {
         "poolInUse" : <num>,
         "poolAvailable" : <num>,
         "poolCreated" : <num>,
         "poolRefreshing" : <num>,
         "cfg1.example.net:27019" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         },
         "cfg2.example.net:27019" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         },
         "cfg3.example.net:27019" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         },
         "shard1.example.net:27018" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         },
         "shard2.example.net:27018" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         }
      },
      "global" : {
         "poolInUse" : <num>,
         "poolAvailable" : <num>,
         "poolCreated" : <num>,
         "poolRefreshing" : <num>,
         "cfg3.example.net:27019" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         },
         "cfg1.example.net:27019" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         },
         "cfg2.example.net:27019" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         },
         "shard2.example.net:27018" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         },
         "shard1.example.net:27018" : {
            "inUse" : <num>,
            "available" : <num>,
            "created" : <num>,
            "refreshing" :<num>
         }
      }
   },
   "hosts" : {
      "cfg3.example.net:27019" : {
         "inUse" : <num>,
         "available" : <num>,
         "created" : <num>,
         "refreshing" :<num>
      },
      "cfg1.example.net:27019" : {
         "inUse" : <num>,
         "available" : <num>,
         "created" : <num>,
         "refreshing" :<num>
      },
      "cfg2.example.net:27019" : {
         "inUse" : <num>,
         "available" : <num>,
         "created" : <num>,
         "refreshing" :<num>
      },
      "shard2.example.net:27018" : {
         "inUse" : <num>,
         "available" : <num>,
         "created" : <num>,
         "refreshing" :<num>
      },
      "shard1.example.net:27018" : {
         "inUse" : <num>,
         "available" : <num>,
         "created" : <num>,
         "refreshing" :<num>
      }
   },
   "replicaSets" : {
      "csRS" : {
         "hosts" : [
            {
               "addr" : "cfg1.example.net:27019",
               "ok" : <bool>,
               "ismaster" : <bool>,
               "hidden" : <bool>,
               "secondary" : <bool>,
               "pingTimeMillis" : <num>
            },
            {
               "addr" : "cfg2.example.net:27019",
               "ok" : <bool>,
               "ismaster" : <bool>,
               "hidden" : <bool>,
               "secondary" : <bool>,
               "pingTimeMillis" : <num>
            },
            {
               "addr" : "cfg3.example.net:27019",
               "ok" : <bool>,
               "ismaster" : <bool>,
               "hidden" : <bool>,
               "secondary" : <bool>,
               "pingTimeMillis" : <num>
            }
         ]
      },
      "shardB" : {
         "hosts" : [
            {
               "addr" : "shard2.example.net:27018",
               "ok" : <bool>,
               "ismaster" : <bool>,
               "hidden" : <bool>,
               "secondary" : <bool>,
               "pingTimeMillis" : <num>
            }
         ]
      },
      "shardA" : {
         "hosts" : [
            {
               "addr" : "shard1.example.net:27018",
               "ok" : <bool>,
               "ismaster" : <bool>,
               "hidden" : <bool>,
               "secondary" : <bool>,
               "pingTimeMillis" : <num>
            }
         ]
      }
   },
   "ok" : 1,
   "$clusterTime" : {
      "clusterTime" : <timestamp>,
      "signature" : <document>
   },
   "operationTime" : <timestamp>
}

Output

connPoolStats.totalAvailable

Reports the total number of available outgoing connections from the current mongod / mongos instance to other members of the sharded cluster or replica set.

connPoolStats.totalCreated

Reports the total number of outgoing connections ever created by the current mongod / mongos instance to other members of the sharded cluster or replica set.

connPoolStats.totalInUse

Reports the total number of outgoing connections from the current mongod / mongos instance to other members of the sharded cluster or replica set that are currently in use.

connPoolStats.totalRefreshing

Reports the total number of outgoing connections from the current mongod / mongos instance to other members of the sharded cluster or replica set that are currently being refreshed.

connPoolStats.replicaSetMatchingStrategy

New in version 5.0.

On a mongos instance, this value reports the policy used by the instance to determine the minimum size limit of its connection pools to nodes within replica sets.

On a mongod instance, this value reports the policy used by the instance to determine the minimum size limit of its connection pools to nodes within other replica sets.

The policy for mongos and mongod can be set with the ShardingTaskExecutorPoolReplicaSetMatching parameter.

Note

If the ShardingTaskExecutorPoolReplicaSetMatching is set to "automatic", the replicaSetMatchingStrategy still describes the actual policy being used, not "automatic". To find the value of the ShardingTaskExecutorPoolReplicaSetMatching, use getParameter which returns the value of the server parameter:

db.adminCommand( { getParameter : 1, "ShardingTaskExecutorPoolReplicaSetMatching" : 1 } )
connPoolStats.numClientConnection

Reports the number of active and stored outgoing synchronous connections from the current mongod / mongos instance to other members of the sharded cluster or replica set.

These connections are a part of a pool that is a subset of the data reported by totalAvailable, totalCreated, and totalInUse.

connPoolStats.numAScopedConnection

Reports the number of active and stored outgoing scoped synchronous connections from the current mongod / mongos instance to other members of the sharded cluster or replica set.

These connections are a part of a pool that is a subset of the data reported by totalAvailable, totalCreated, and totalInUse.

connPoolStats.pools

Reports on connection statistics (in use/available/created/refreshing) grouped by the connection pools. A mongod or mongos has two distinct families of outgoing connection pools:

  • DBClient-based pools (the "write path") and

  • NetworkInterfaceTL-based pools (the "read path").

For each pool, the command returns a document that resembles the following:

{
  "poolInUse" : <num>,
  "poolAvailable" : <num>,
  "poolCreated" : <num>,
  "poolRefreshing" : <num>,
  "[host1]" : { "inUse" : <num>, "available" : <num>, "created" : <num>, "refreshing" : <num> },
  "[host2]" : { "inUse" : <num>, "available" : <num>, "created" : <num>, "refreshing" : <num> },
  ...
}

Note

If there are no connections (in use/available/created/refreshing) for a particular pool, the connPoolStats does not return statistics for that pool.

connPoolStats.pools.NetworkInterfaceTL-TaskExecutorPool-[n]

Displays connection statics related to TaskExecutor pools. Typically, there will be one TaskExecutorPool per core, e.g. pools.NetworkInterfaceTL-TaskExecutorPool-0 ... pools.NetworkInterfaceTL-TaskExecutorPool-7 for an 8-core processor.

Tip

See also:

taskExecutorPoolSize

connPoolStats.pools.NetworkInterfaceTL-ShardRegistry

Available if the command is run on a member of a sharded cluster.

Displays the pool statistics for the connections between the current mongod / mongos instance and other members of the sharded cluster.

connPoolStats.pools.NetworkInterfaceTL-Replication

Available if the command is run on a member of a replica set.

Displays the pool statistics for the connections between the current mongod instance and the other members of the replica set.

connPoolStats.pools.global

Displays the DBClient-based pool statistics.

connPoolStats.hosts

Reports on connection statistics (in use/available/created/refreshing) grouped by the hosts.

Contains documents that represent a report of connections between the current mongod / mongos instance and each member of the sharded cluster or replica set.

connPoolStats.hosts.[host].available

Reports the total number of connections available for connecting to the [host].

connPoolStats.hosts.[host].created

Reports the number of connections to the [host] ever created.

connPoolStats.hosts.[host].inUse

Reports the number of connections to the [host] that are currently in use.

connPoolStats.replicaSets

Contains documents that represent a report of information related to each replica set connected to the current mongod / mongos.

connPoolStats.replicaSets.replicaSet

Reports on each replica set connected to the current mongod / mongos.

connPoolStats.replicaSets.[replicaSets].hosts

Holds an array of documents that reports on each member in the replica set.

These values derive from the replica set status values.

connPoolStats.replicaSets.[replicaSet].hosts[n].addr

Reports the address for the member in the replica set in [hostname]:[port] format.

connPoolStats.replicaSets.[replicaSet].hosts[n].ok

Reports false when:

  • the current mongos or mongod cannot connect to instance.

  • the current mongos or mongod received a connection exception or error.

This field is for internal use.

connPoolStats.replicaSets.[replicaSet].hosts[n].ismaster

Reports true if this host is the primary member of the replica set.

connPoolStats.replicaSets.[replicaSet].hosts[n].hidden

Reports true if this host is a hidden member of the replica set.

connPoolStats.replicaSets.[replicaSet].hosts[n].secondary

Reports true if this host is a secondary member of the replica set.

connPoolStats.replicaSets.[replicaSet].hosts[n].pingTimeMillis

Reports the ping time in milliseconds from the mongos or mongod to this host.

connPoolStats.replicaSets.[replicaSet].hosts[n].tags

Reports the members[n].tags, if this member of the set has tags configured.

See also Response for details on the ok status field, the operationTime field and the $clusterTime field.

host

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