A Data Flow Parallel Activity has a setting called “Activity Start Interval”. Activity Start Interval specifies the time in seconds elapsed between the start of each activity. For example, if the value is 0.2, the activities will start at a 0.2 seconds interval. The reason you’d want to use this setting is that on some systems, you may experience connection pool problems when the activities are started to rapidly. As a result, the Data Flow activities will fail to start and you will get the following error message in the log.
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.
Setting the Activity Start Interval to a higher value will fix this problem.