Spike testing

Spike testing assesses how well your system handles sudden, extreme surges in user load. This performance test simulates massive spikes in traffic to verify that your system can handle the surge and recover quickly without crashing or losing data. 

Here's what spike testing looks like in real scenarios: 

Spike testing helps prevent system failures during critical high-traffic moments. It reveals how your system degrades under pressure and whether it can recover gracefully. 

For businesses where unexpected traffic surges are common (like retail during Black Friday), spike testing is essential to prevent lost revenue and damaged reputation from outages. 

Creating realistic spike tests is tough—you need specialized tools and environments that can generate massive load quickly. Many teams struggle to simulate true production conditions or identify the root cause of performance issues under extreme load. 

Spike testing is a type of performance test where the number of requests is increased (very quickly) up to stress levels, then decreased again while the test continues to assess performance. Spikes in traffic can either happen randomly or after constant intervals. Two things could happen during significant spikes in traffic; either response times could increase, but you'd still have a working system, or you'd get more error responses.

As shown on the diagram, the application / service is facing an unusual traffic for a specific period of time and after that, it is returned to the expected application load.

For example, an e-commerce site promoting a 1 hour exceptional discount might expect to see their user count spike leading up to and during that hour, following which it will return to the normal user load or slightly higher.

In another example, an online marketplace might release tickets to see your favourite band at a fixed time. User load spikes at this time until the tickets are unavailable and then returns to normal load.

Many systems have some auto-scaling built into them. The usual ramp-up speed in a stress test gives such systems ample time to provision new resources and run the internal maintenance routines that are required to stay performant. With spike tests, however, changes in traffic come about abruptly. They happen faster than the system usually reacts. It's vital to understand the behavior of the software and its underlying infrastructure in these cases to achieve good scalability.