I wrote:
Basically this is a query of the form 'Please suggest open source alternatives to proprietary package X', which generically (1) presupposes intimate knowledge of proprietary package X and (2) implicitly assumes that the pinnacle of success would be replicating package X's feature set, as opposed to doing something smarter and more useful-to-you.
Perhaps you should back up and describe what specific real-world problem you're trying to solve.
Or, as Stackoverflow.com puts it on, e.g., http://stackoverflow.com/questions/5903825/are-there-any-comparable-framewor... : Questions asking us to recommend or find a book, tool, software library, tutorial or other off-site resource are off-topic for Stack Overflow as they tend to attract opinionated answers and spam. Instead, describe the problem and what has been done so far to solve it. Some of the links on that page may be useful, such as the ones to 'Performing a Stress Test on Web Application?' and 'Open source Load Testing framework' -- depending, of course, on what specific real-world problem you are trying to solve.