Key takeaways
- Endurance testing and soak testing are the same thing: normal load held for a long time.
- It finds the failures that need hours to appear, which is why a thirty-minute load test never sees them.
- Compare the first hour with the last hour. Degradation over time is the entire result.
The quick answer
Endurance testing runs a system at expected load for an extended period, typically many hours, to find problems that only appear with time rather than with volume. Soak testing is the same practice under a different name. The question it answers is not “can it handle this load” but “can it handle this load all day”.
Is Your Infrastructure Ready for Global Traffic Spikes?
Unexpected load surges can disrupt your services. With LoadFocus’s cutting-edge Load Testing solutions, simulate real-world traffic from multiple global locations in a single test. Our advanced engine dynamically upscales and downscales virtual users in real time, delivering comprehensive reports that empower you to identify and resolve performance bottlenecks before they affect your users.
Endurance testing and soak testing: is there a difference?
In practice, no. Both describe holding a realistic load steady for a long duration and watching for drift. Some teams use soak testing for the longest runs and endurance testing for anything sustained, but the technique is identical and the two terms are used interchangeably across the industry.
What endurance testing finds
Everything here shares a property: it needs time to accumulate, so a short test passes cleanly.
- Memory leaks. The classic finding. Memory that is allocated and never released climbs slowly until the process is restarted or killed.
- Connection leaks. Database or HTTP connections that are opened and not returned to the pool. The pool drains over hours and then every request queues.
- Disk and log growth. Logs, temp files and audit rows filling a volume nobody sized for a sustained run.
- Cache degradation. Caches that grow without eviction, or whose hit rate falls as the working set drifts.
- Scheduled work colliding with traffic. Backups, batch jobs and cleanup tasks that only fire once a day and were never observed under load.
- Third-party quotas. Daily rate limits that a short test never approaches.
How long should an endurance test run?
Long enough to cross at least one natural cycle of the system. If a batch job runs hourly, several hours. If the meaningful cycle is a nightly backup, the run needs to span it. A common practical choice is eight hours, because it covers a working day and most scheduled work, but the right answer is set by your system rather than by convention.
Think your website can handle a traffic spike?
Fair enough, but why leave it to chance? Uncover your website’s true limits with LoadFocus’s cloud-based Load Testing for Web Apps, Websites, and APIs. Avoid the risk of costly downtimes and missed opportunities—find out before your users do!
Running for a long time at an unrealistically high load is a different test. Endurance testing uses normal, expected traffic. Pushing beyond it is stress testing, and mixing the two makes the result hard to attribute.
What to measure
The metrics matter less than the comparison. Capture response time, throughput, error rate, memory, connection pool usage and disk, then compare the beginning of the run with the end.
- Response time should be flat. A slow upward slope over hours is the signal.
- Memory should reach a plateau. A line that never stops rising is a leak, however gentle the gradient.
- Error rate should stay at zero or at its normal floor. Errors that begin only in the final hours point at something exhausting.
- Throughput should hold. Falling throughput at constant load means the system is doing more work per request than it was.
Reading the result
Flat lines
A run where the last hour looks like the first is a pass, and it is the only kind of evidence that a system is safe to leave running.
A slow slope
Gradual degradation is the most valuable finding, because it is invisible in production until it is an incident. Extrapolate the gradient: if response time rises by a small amount every hour, work out when it crosses your threshold.
LoadFocus is an all-in-one Cloud Testing Platform for Websites and APIs for Load Testing, Apache JMeter Load Testing, Page Speed Monitoring and API Monitoring!
A step change
A sudden shift partway through usually coincides with an event rather than with accumulation. Line the timestamp up against scheduled jobs, deploys and log rotation before assuming it is a leak.
Frequently Asked Questions
Is soak testing different from endurance testing?
No, they are two names for the same practice: holding a realistic load for an extended period to find degradation over time. Use whichever term your team already uses.
Why not just run a longer load test?
That is exactly what this is. The distinction is intent: an endurance test is designed to be compared start against end, so the setup captures trend data rather than a single summary.
What if the system is restarted regularly?
Then run the test for longer than the interval between restarts. If a nightly restart is what keeps a memory leak from mattering, that is worth knowing explicitly rather than by accident.