If you’re load testing an app with Ajax that uses polling, or comet, using an http level test (no browser), don’t assume you can safely re-use your script in subsequent load tests. If a developer changes the polling interval, your script will no longer be accurate and the load it generates may be substantially less or more intense than real world traffic. A change like this is easy to miss. Also, if you don’t have content-checks on your Ajax actions, other changes may invalidate your script without you ever realizing it.
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