To conserve resources, vRealize Automation limits the number of concurrently running instances of machine provisioning and data collection. You can change the limits.
Configuring Concurrent Machine Provisioning vRealize Automation . You can make some changes to limits placed on proxy agents and workflow activities to alter performance. Configuring Concurrent Data Collections vRealize Automation limits concurrent data collection activities. If you change this limit, you can avoid unnecessary timeouts by changing the default execution timeout intervals for the different types of data collection. Adjust Concurrency Limits and Timeout Intervals Adjust Execution Frequency of Machine Callbacks vRealize Automation callback procedure is run for changed machine leases.