Shared Instance Pool Database Connections

[mpboyle]

We recently moved some of our low priority services to the shared instance pool on our ArcGIS Server.  One thing we noticed almost immediately after moving these services is that we have A LOT more connections to our enterprise databases.

We log the number of connections to our enterprise databases so we have a good baseline of the number of connections to expect, and once we moved these services to our shared instance pool, the number of connections exploded.

Is this an expected behavior of the shared instance pool?  Has anyone else noticed this?  Does this have any negative affects on performance for the database?

Below is a query showing the number of connections to our enterprise databases, and you can see after we moved services to the shared instance pool, at around 9am on Wednesday (10/14/2020) the number of connections ballooned.  The previous day, Tuesday 10/13/2020 shows our typical number of connections.

Environment Settings

ArcGIS Enterprise 10.7.1 (Portal, Server, Data Store, Web Adaptor) --- each component is installed on a separate server

RDBMS: Sql Server 2014 Standard

Number of shared instances per machine: 4

[SiCasley]

We've also noticed something similar with our PostgreSQL enterprise database and AGS 10.8.1. 

Does anyone know of any documentation on how the shared instance pool handles database connections? Is there any way to control how long AGS will keep an idle database connection open or any way to force those connections to be recycled?

[VenusScott]

Not sure about the database connections BUT we found the default in ArcPro when publishing map/feature services is set to "Enable Schema Locking" as defaulted to "YES". This has been a big issue for us especially if it's just a viewing map service!