7. Orchestration and Extension : 7.4 vCenter Orchestrator : 7.4.2 Scalability
7.4.2 Scalability
When configuring vCenter Orchestrator to run a numerous concurrent workflows, it is necessary to understand how the Orchestration engine works.
The vCenter Orchestrator Workflow Engine default configuration allows for running up to 300 concurrent workflows. When the running queue exceeds this number, the workflows are placed in an execution queue and moved back to the running queue as soon as one or more workflows have completed an execution run. Completed workflow states can be “completed successfully,” “failed”, “canceled” or "passivated" (waiting-for-signal state). The execution queue has a default size of 10000 workflows. If the execution queue size is exceeded, the workflow engine marks subsequent workflows as failed.
A running workflow consumes at least one running thread (either running the workflow or updating the workflow state) and from 1MB to a few megabytes of memory (varies depending on the number of enabled plug-ins and plug-in objects). Limiting the number of workflows allows allocation of threads and memory, with the maximum depending on the JVM settings, the operating system, and the underlying hardware.
To change the default value, change the following properties in the Orchestrator\appserver\server\vmo\conf\vmo.properties configuration file:
NoteVMware recommends following the guidelines in the rest of this document before increasing the default settings for the concurrent workflows because doing so requires expanding the resources for the vCenter Orchestrator Java virtual machine, the host operating system, the host virtual machine, and possibly the vCenter Orchestrator Database.
Each active plug-in has an impact on the workflow engine performance. A plug-in loads classes, runs update threads, logs information to disk, provides objects to the scripting engine, and maintains the inventory. Even if the plug-in is unused, it consumes resources and increases the memory footprint of each running workflow. Disable all plug-ins that are not in use to increase the workflow engine capacity.