Performance Testing !!!!
Printed From: One Stop Testing
Category: Types Of Software Testing @ OneStopTesting
Forum Name: Performance & Load Testing @ OneStopTesting
Forum Discription: Discuss All that is need to be known about Performance & Load Testing and its Tools.
URL: http://forum.onestoptesting.com/forum_posts.asp?TID=2880
Printed Date: 30Nov2024 at 9:01pm
Topic: Performance Testing !!!!
Posted By: tanushree
Subject: Performance Testing !!!!
Date Posted: 15Oct2007 at 4:58am
Performance Testing
In
software engineering, performance testing is testing that is performed
to determine how fast some aspect of a system performs under a
particular workload.
Performance testing can serve different
purposes. It can demonstrate that the system meets performance
criteria. It can compare two systems to find which performs better. Or
it can measure what parts of the system or workload cause the system to
perform badly. In the diagnostic case, software engineers use tools
such as profilers to measure what parts of a device or software
contribute most to the poor performance or to establish throughput
levels (and thresholds) for maintained acceptable response time.
In
performance testing, it is often crucial (and often difficult to
arrange) for the test conditions to be similar to the expected actual
use.
Technology
Performance
testing technology employs one or more PCs to act as injectors – each
emulating the presence or numbers of users and each running an
automated sequence of interactions (recorded as a script, or as a
series of scripts to emulate different types of user interaction) with
the host whose performance is being tested. Usually, a separate PC acts
as a test conductor, coordinating and gathering metrics from each of
the injectors and collating performance data for reporting purposes.
The usual sequence is to ramp up the load – starting with a small
number of virtual users and increasing the number over a period to some
maximum.
The test result shows how the performance varies with
the load, given as number of users vs response time. Various tools,
including Compuware Corporation's QACenter Performance Edition, are
available to perform such tests. Tools in this category usually execute
a suite of tests which will emulate real users against the system.
Sometimes the results can reveal oddities, e.g., that while the average
response time might be acceptable, there are outliers of a few key
transactions that take considerably longer to complete – something that
might be caused by inefficient database queries, etc.
Performance
testing can be combined with stress testing, in order to see what
happens when an acceptable load is exceeded –does the system crash? How
long does it take to recover if a large load is reduced? Does it fail
in a way that causes collateral damage?
Performance specifications
Performance
testing is frequently not performed against a specification, i.e. no
one will have expressed what is the maximum acceptable response time
for a given population of users. However, performance testing is
frequently used as part of the process of performance profile tuning.
The idea is to identify the “weakest link” – there is inevitably a part
of the system which, if it is made to respond faster, will result in
the overall system running faster. It is sometimes a difficult task to
identify which part of the system represents this critical path, and
some test tools come provided with (or can have add-ons that provide)
instrumentation that runs on the server and reports transaction times,
database access times, network overhead, etc. which can be analysed
together with the raw performance statistics. Without such
instrumentation one might have to have someone crouched over Windows
Task Manager at the server to see how much CPU load the performance
tests are generating. There is an apocryphal story of a company that
spent a large amount optimising their software without having performed
a proper analysis of the problem. They ended up rewriting the system’s
‘idle loop’, where they had found the system spent most of its time,
but even having the most efficient idle loop in the world obviously
didn’t improve overall performance one iota!
Performance testing
almost invariably identifies that it is parts of the software (rather
than hardware) that contribute most to delays in processing users’
requests.
Performance testing can be performed across the web,
and even done in different parts of the country, since it is known that
the response times of the internet itself vary regionally. It can also
be done in-house, although routers would then need to be configured to
introduce the lag what would typically occur on public networks.
It
is always helpful to have a statement of the likely peak numbers of
users that might be expected to use the system at peak times. If there
can also be a statement of what constitutes the maximum allowable 95
percentile response time, then an injector configuration could be used
to test whether the proposed system met that specification.
Tasks to undertake
Tasks to perform such a test would include:
* Analysis of the types of interaction that should be emulated and the production of scripts to do those emulations
* Decision whether to use internal or external resources to perform the tests.
* set up of a configuration of injectors/controller
*
set up of the test configuration (ideally identical hardware to the
production platform), router configuration, quiet network (we don’t
want results upset by other users), deployment of server
instrumentation.
* Running the tests – probably repeatedly in order to see whether any unaccounted for factor might affect the results.
* Analysing the results, either pass/fail, or investigation of critical path and recommendation of corrective action.
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Replies:
Posted By: getzephyr
Date Posted: 24May2008 at 1:09am
In
my opinion performance
testing is the process of determining the speed or effectiveness of a
computer, network, software program or device. This process can
involve quantitative tests done in a lab, such as measuring the
response time or the number of MIPS (millions of instructions per
second) at which a system functions. Qualitative attributes such as
reliability, scalability and interoperability may also be evaluated.
Performance testing is often done in conjunction with stress testing.
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Posted By: kalai
Date Posted: 25Jun2009 at 8:05am
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Performance testing is testing related to speed, scalability and stability.
http://www.macrotesting.com - World Of Software Testing
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