We are currently running Document Exchange 6.0.4. Recently we upgraded the DNN installation from 5,6.8 to 9.1.1.
Immediately after installation, about once per day, the site would become unresponsive and I would see the classic symptoms of the DB connection pool having reached its limit (100 connections): a very large number of SQL SPIDs active (e.g. if you run sp_who2 on the DB), and these errors in the Windows App log:
Exception type: InvalidOperationException
Exception message: Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.
at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
at System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
at DotNetNuke.Data.PetaPoco.PetaPocoExt.ExecuteReader(Database database, String sql, Object args) in C:\TeamCity\buildAgent\work\DNN_Platform_910_Public\Packaging\DNN.Platform\DNN Platform\Library\Data\PetaPoco\PetaPocoExt.cs:line 52
By a process of elimination (disabling all scheduled tasks then re-enabling a few at a time) I determined it was almost certainly due to one of the following scheduled tasks:
DMX Maintenance Task
DMX Service Task
I know we are running a very old DMX version on a DNN version it was not designed for. Everything seems to be working however, except for this issue. We will upgrade DMX if we know that the above issue is known and fixed in a later version.