Within the Identity Manager repository, a workflow exists as a configuration object, typically of Type WFProcess. (The single exception to this object definition is the Create User workflow, which is defined as a ProvisioningTask object.) The taskType is always Workflow.
Identity Manager does not lock the repository object (that is, the User) while a workflow is executing. This is because workflows can run for days, and the repository object cannot remain unlocked for that long. However, Identity Manager prevents you from launching another update workflow on the same user.