Scalability Planning


  • Determine the limits of the number of devices that can be interacted with via a single Volttron platform.

  • Determine how scaling out affects the rate at which devices are scraped. i.e. How long from the first device scrape to the last?

  • Determine the effects of socket throttling in the platform driver on the performance of Modbus device scraping.

  • Measure total memory consumption of the Platform Driver Agent at scale.

  • Measure how well the base history agent and one or more of the concrete agents handle a large amount of data.

  • Determine the volume of messages that can be achieved on the pubsub before the platform starts rejecting them.

Test framework

Test Devices

Simple, command line configured virtual devices to test against in both Modbus and BACnet flavors. Devices should create 10 points to read that generate either random or easily predictable (but not necessarily constant) data. Process should be completely self contained.

Test devices will be run on remote hosts from the Volttron test deployment.

Launcher Script

  • The script will be configurable as to the number and type of devices to launch.

  • The script will be configurable as to the hosts to launch virtual devices on.

  • The script (probably a fabric script) will push out code for and launch one or more test devices on one or more machines for the platform to scrape.

  • The script will generate all of the platform driver configuration files to launch the platform driver.

  • The script may launch the platform driver.

  • The script may launch any other agents used to measure performance.

Shutdown Script

  • The script (probably the same fabric script run with different options) will shutdown all virtual drivers on the network.

  • The script may shutdown the platform driver.

  • The script may shutdown any related agents.

Performance Metrics Agent

This agent will track the publishes by the different drivers and generate data in some form to indicate:

  • Total time for all devices to be scraped

  • Any devices that were not successfully scraped.

  • Performance of the message bus.

Additional Benefits

Most parts of a test bed run should be configurable. If a user wanted to verify that the Platform Driver worked, for instance, they could run the test bed with only a few virtual device to confirm that the platform is working correctly.

Running a simple test

You will need 2 open terminals to run this test. (3 if you want to run the platform in it’s own terminal)
Checkout the feature/scalability branch.

Start the platform.

Go to the volttron/scripts/scalability-testing directory in two different terminals. (Both with the environment activated)

In one terminal run:

python --count=1500 --scalability-test --scalability-test-iterations=6 fake fake18.csv localhost

Change the path to fake.csv as needed.

(Optional) After it finishes run:


to start the null historian.

In a separate terminal run:


to start the scalability test.

This will emulate the scraping of 1500 devices with 18 points each 6 times, log the timing, and quit.

Redirecting the driver log output to a file can help improve performance. Testing should be done with and without the null historian.

Currently only the depth first all is published by drivers in this branch. Uncomment the other publishes in to test out full publishing. fake.csv has 18 points.

Optionally you can run two listener agents from the volttron/scripts directory in two more terminals with the command:


and rerun the test to see the how it changes the performance.

Real Driver Benchmarking

Scalability testing using actual MODBUS or BACnet drivers can be done using the virtual device applications in the scripts/scalability-testing/virtual-drivers/ directory. The configuration of the platform driver and launching of these virtual devices on a target machine can be done automatically with fabric.


This requires two computers to run: One for the VOLTTRON platform to run the tests on (“the platform”) and a target machine to host the virtual devices (“the target”).

Target setup

The target machine must have the VOLTTRON source with the feature/scalability branch checked out and bootstrapped. Make a note of the directory of the VOLTTRON code.

Platform setup

With the VOLTTRON environment activated install fabric.

pip install fabric

Edit the file scripts/scalability-testing/ as needed.

  • virtual_device_host (string) - Login name and IP address of the target machine. This is used to remotely start and stop virtual devices via ssh. “volttron@

  • device_types - map of driver types to tuple of the device count and registry config to use for the virtual devices. Valid device types are “bacnet” and “modbus”.

  • volttron_install - location of volttron code on the target.

To configure the driver on the platform and launch the virtual devices on the target run

fab deploy_virtual_devices

When prompted enter the password for the target machine. Upon completion virtual devices will be running on the target and configuration files written for the platform driver.

Launch Test

If your test includes virtual BACnet devices be sure to configure and launch the BACnet Proxy before launching the scalability driver test.



to start the null historian.

In a separate terminal run:


to start the scalability test.

To stop the virtual devices run

fab stop_virtual_devices

and enter the user password when prompted.