Question:
I'm looking for a CLEAR definition of stress and load testing (what is in
fact the main difference between both?)
Answer:
I'm not a native speaker either but I would say,
stress testing means pushing load testing to the limits of the system
under test.
This question was entertained only a few days ago. Perhaps you missed
that discussion? I hope I offend no one by taking the liberty of
re-posting Dr. Beizer's response to the original question below.
Stress testing is subjecting a software system to an unreasonable load
while
denying it the resources needed to process that load.
Load testing is subjecting a properly configured system (e.g., adequate
resources) to a statistically valid peak load in order to see that the
system's throughput/response is in accordance to specifications -- and
incidently, to find any load-dependent bugs.
The objective in load testing is to experimentally determine the
throughput/delay function of the system for the transactions of
interest.
This is done by using a simulated load that closely matches the expected
users' operational profile.
The objectives are totally different, as are the methods. In
stress
testing the objective is to force unusual synchronization and timing
situations (e.g., even sequence ordering) in order to expose such
synchronization bugs as may exist. The system under stress is not
expected to
process a stress load, but to behave decently -- such as shutting down,
throttling, etc. but not losing control. What "decent" means depends on
the
application. Often, stress testing is done with an anti-profile. That
is, a
profile in which all probability distributions in the profile are
inverted
The MAIN difference seems to be that performance under load is important
for many users of most applications, while performance under stress is
of importance in applications whose behavior is critical under all
conditions.
It is not necessary to utilize a load to put a system into stress,
however, processing an excessive load over an extended duration is one
method of producing stress.
You might also refer to the FAQ for suggested readings and other
references
which might provide additional information on this topic. If you feel
that these definitions lacks clarity in some regard, a more focused
question might help to enlighten us all.
