Enterprise applications are often business critical but lack effective
synthetic workload generation techniques to evaluate performance. These
workloads are characterized by sessions of interdependent requests that
often cause and exploit dynamically generated responses. Interrequest
dependencies must be reflected in synthetic workloads for these systems
to exercise application functions correctly. This poses significant
challenges for automating the construction of representative synthetic
workloads and manipulating workload characteristics for sensitivity
analyses. This paper presents a technique to overcome these problems.
Given request logs for a system under study, the technique automatically
creates a synthetic workload that has specified characteristics and
maintains the correct interrequest dependencies. The technique is
demonstrated through a case study involving a TPC-W e--commerce system.
Results show that incorrect performance results can be obtained by
neglecting interrequest dependencies, thereby highlighting the value of
our technique. The study also exploits our technique to investigate the
impact of several workload characteristics on system performance.
Results establish that high variability in the distributions of session
length, session idle times, and request service times can cause
increased contention among sessions, leading to poor system
responsiveness. To the best of our knowledge, these are the first
results of this kind for a session-based system. We believe our
technique is of value for studies where fine control over workload is
essential.