Description:

This changes the taskExecutorPoolSize server param to 1 (from the current default of 0, which implies 4 <= NUM_CORES <= 64 egress connection pools on a mongos).

It also introduces AsyncRequestsSenderUseBaton, which is a true by default boolean server parameter which controls a targetted linux only performance optimization. Old behavior can be restored by setting taskExecutorPoolSize=0 and AsyncRequestsSenderUseBaton=false.

Windows and os x constrain the pool size without any os specific performance optimization (so may need the above values altered if a perf regression is detected)

Scope of changes:

• parameters
• 4.0
• 4.0-compatibility
• connPoolStats output

Impact to other docs outside of this product:

MVP:

Resources:

Engineering Ticket Description:

This changes the default to 1 for the task executor pool (meaning we also have 1 egress connection pool for user operations in mongos).

In order to mitigate the performance hit, a targetted optimization has been added for linux which uses client-thread based polling in the ARS.

Scope of changes:

Impact to other docs outside of this product:

MVP:

Resources: