DOCS-15465 mongos connection pool (BACKPORT) (#1420)

* Docs-15280 mongos connection pool (#1311)

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

* DOCS-15280-mongos-connection-pool

Co-authored-by: jason-price-mongodb <[email protected]>

* DOCS-15465-BACKPORT mongo connection pool sizing

* DOCS-15465-BACKPORT mongo connection pool sizing

Co-authored-by: jason-price-mongodb <[email protected]>

Author: jason-price-mongodb

source/reference/parameters.txt

@@ -2294,7 +2294,54 @@ Sharding Parameters
    pools, where ``n`` is the number of cores. See
    :parameter:`taskExecutorPoolSize`.
 
-   .. seealso:: :parameter:`ShardingTaskExecutorPoolMinSize`
+   .. seealso::
+
+      :parameter:`ShardingTaskExecutorPoolMinSize`
+
+.. parameter:: ShardingTaskExecutorPoolMaxSizeForConfigServers
+
+   .. versionadded:: 4.2.22
+
+   Type: integer
+
+   Default: -1
+
+   |both|
+
+   Optional override for :parameter:`ShardingTaskExecutorPoolMaxSize` to
+   set the maximum number of outbound connections each TaskExecutor
+   connection pool can open to a :ref:`configuration server
+   <sharding-config-server>`.
+
+   When set to:
+       
+   - ``-1``, :parameter:`ShardingTaskExecutorPoolMaxSize` is used. This
+     is the default.
+       
+   - an integer value greater than ``-1``, overrides the
+     maximum number of outbound connections each TaskExecutor
+     connection pool can open to a configuration server.
+
+   Parameter only applies to sharded deployments.
+
+   The following example sets
+   :parameter:`ShardingTaskExecutorPoolMaxSizeForConfigServers` to ``2``
+   during startup, which sets the maximum number of outbound connections
+   each TaskExecutor connection pool can open to a configuration server
+   to ``2``:
+
+   .. code-block:: bash
+
+      mongos --setParameter ShardingTaskExecutorPoolMaxSizeForConfigServers=2
+
+   During runtime, you can also set the parameter with the
+   :dbcommand:`setParameter` command:
+
+   .. code-block:: javascript
+
+      db.adminCommand( { setParameter: 1, ShardingTaskExecutorPoolMaxSizeForConfigServers: 2 } )
+
+.. _sharding-pool-minsize-parameters:
 
 .. parameter:: ShardingTaskExecutorPoolMinSize
 
@@ -2334,6 +2381,49 @@ Sharding Parameters
 
    .. seealso:: :parameter:`ShardingTaskExecutorPoolMaxSize`
 
+.. parameter:: ShardingTaskExecutorPoolMinSizeForConfigServers
+
+   .. versionadded:: 4.2.22
+
+   Type: integer
+
+   Default: -1
+
+   |both|
+
+   Optional override for :parameter:`ShardingTaskExecutorPoolMinSize` to
+   set the minimum number of outbound connections each TaskExecutor
+   connection pool can open to a :ref:`configuration server
+   <sharding-config-server>`.
+
+   When set to:
+       
+   - ``-1``, :parameter:`ShardingTaskExecutorPoolMinSize` is used. This
+     is the default.
+       
+   - an integer value greater than ``-1``, overrides the
+     minimum number of outbound connections each TaskExecutor
+     connection pool can open to a configuration server.
+
+   Parameter only applies to sharded deployments.
+
+   The following example sets
+   :parameter:`ShardingTaskExecutorPoolMinSizeForConfigServers` to ``2``
+   during startup, which sets the minimum number of outbound connections
+   each TaskExecutor connection pool can open to a configuration server
+   to ``2``:
+
+   .. code-block:: bash
+
+      mongos --setParameter ShardingTaskExecutorPoolMinSizeForConfigServers=2
+
+   During runtime, you can also set the parameter with the
+   :dbcommand:`setParameter` command:
+
+   .. code-block:: javascript
+
+      db.adminCommand( { setParameter: 1, ShardingTaskExecutorPoolMinSizeForConfigServers: 2 } )
+
 .. parameter:: ShardingTaskExecutorPoolRefreshRequirementMS
 
    Type: integer