Load Testing through Remote Device Simulation
Designing an enterprise-ready application requires extensive testing and quality assurance. This includes all sorts of tests, of course, from examining the user interface for flaws to verifying there is correct logic in all background services. However, no area of testing is more important than scalability. Load testing is how to test the application to ensure it still functions as desired when remote things are connected and streaming information to the Platform.
Load testing is considered a critical component of the change management process. It is mentioned numerous times throughout PTC best practice documentation. This tutorial will step you through designing a load test using Kepware as a simulator. Kepware is free to download and use in short demos, making it the perfect tool for this type of test.
Start by acquiring the latest version of Kepware from the download site. Click “Download Free Demo” if a license was not included in your PTC product package. The installation of Kepware is simple, and for details, see the Kepware Installation Guide. The tutorial shown here uses Kepware version 6.7 and ThingWorx version 8.4.4. Given that we are testing a ThingWorx application, this tutorial assumes ThingWorx is already installed and configured correctly.
Once Kepware is installed, follow these steps:
(This tutorial was developed by Desheng Xu and edited by Victoria Tielebein. Exact specifications of the equipment used in both large scale and local tests are given in step VI, which discusses the size of the simulation)
A full test of 40 channels each with 10 devices was performed as shown in the screenshots here. This simulates 10,000 writes per second to the Platform total, or about 400 remote device connections. This test used the following hardware specifications:
A local test was also run on Windows 10 (64-bit), using the H2 database, with Kepware and ThingWorx running side by side on the machine, 4 cores, 16G. This test made use of only 2 channels, with 10 devices each. For local tests to see how the simulation works, this is fine, but a more robust set-up like the above will be needed in a true load test.
If there is not enough memory on the machine hosting Kepware, errors like this will appear in the Kepware logs: One or more value change updates lost due to insufficient space in the connection buffer. Once you decide on the number of tags and devices needed, follow the steps below to add them.
This tutorial is a very basic way to simulate many remote devices ingesting data into the Platform. For this to be a true test of the application, the remote things created in this test will need to be given business logic tasks as well. The AutoKepwareCreate service can be modified to give any template (and not just RemoteThing) to the thing template which is created and subsequently passed into the demo devices. Likewise, the template itself can be created, and then manually modified to look like the actual remote device template in the application, before the rest of the things are created (using the IgnoreTemplate flag in the creation and deletion services, as discussed above).
Ensure that events are triggered as expected and that subscriptions to property updates are in place on the thing template before creating the demo things. Make use of the subsystem monitor to ensure that the event, value stream, and stream queues do not grow so large that the Platform cannot keep up with the requests (for details about tuning the stream and value stream processing subsystems, see PTC’s best practice documentation). Also be sure to load some of the mashups to see how they perform while the ingestion test is happening. This will test whether or not the ingestion rate and business logic of the application can function side by side without errors, data loss, or performance issues.