Effective scripting – Use scripting development design guidelines to avoid unnecessary and highly resource-demanding operations such as active wait loops, repetitive expensive calls to the same resources, and ineffective algorithms. Perform extensive testing on a vCenter Orchestrator test server before running new or updated workflows on a production system.

Workflow threading control – Having many distinct running workflows increases the amount of resources are used.

Workflows started individually and workflows started using the Asynchronous Workflow or Nested Workflow palette elements run in different workflow instances.

A sub-workflow in a master workflow still runs within the same workflow instance, but uses fewer resources. Link the workflows in higher-level workflows instead of calling individual workflows in sequence.

Reduce the number of waiting workflows – If the reason for the high concurrency is due to a high number of workflows waiting on external systems, the following methods can help avoid consuming resources while waiting:

The Wait Until date workflow palette element and the System.Sleep() methods keep the workflow in a running state in the execution queue. Even if the thread is in Sleep mode, it still consumes memory. For long running workflows, these can be replaced by the waiting timer or waiting event palette elements. Using one of these elements passivates the workflow execution and saves its state in the vCenter Orchestrator database. The workflow is then removed from the running queue and memory is freed. The vCloud Director library’s long running workflows make extensive use of the waiting event palette element.

When workflow activity must be suspended until a determined time, programmatically schedule a workflow task.

Do not trigger a large number of these at the same time.

Do not set very short timers in loops.