Stress testing
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Stress testing (sometimes called torture testing) is a form of deliberately intense or thorough testing used to determine the stability of a given system, critical infrastructure or entity. It involves testing beyond normal operational capacity, often to a breaking point, in order to observe the results. Reasons can include: * to determine breaking points or safe usage limits * to confirm mathematical model is accurate enough in predicting breaking points or safe usage limits * to confirm intended specifications are being met * to determine modes of failure (how exactly a system fails) * to test stable operation of a part or system outside standard usage Reliability engineers often test items under expected stress or even under accelerated stress in order to determine the operating life of the item or to determine modes of failure. The term " stress" may have a more specific meaning in certain industries, such as material sciences, and therefore stress testing may sometimes have a technical meaning – one example is in
fatigue testing Fatigue testing is a specialised form of mechanical testing that is performed by applying Structural load#Types, cyclic loading to a ''coupon'' or structure. These tests are used either to generate Fatigue (material), fatigue life and crack grow ...
for materials.


Computing


Hardware

Stress testing, in general, should put computer hardware under exaggerated levels of stress in order to ensure stability when used in a normal environment. These can include extremes of workload, type of task, memory use, thermal load (heat), clock speed, or voltages. Memory and CPU are two components that are commonly stress tested in this way. There is considerable overlap between stress testing software and
benchmarking Benchmarking is the practice of comparing business processes and performance metrics to industry bests and best practices from other companies. Dimensions typically measured are Project management triangle, quality, time and cost. Benchmarking i ...
software, since both seek to assess and measure maximum performance. Of the two, stress testing software aims to test stability by trying to force a system to fail; benchmarking aims to measure and assess the maximum performance possible at a given task or function. When modifying the operating parameters of a
CPU
CPU
, such as
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...

temperature
,
overclocking In computing, overclocking is the practice of increasing the clock rate of a computer to exceed that certified by the manufacturer. Commonly, operating voltage is also increased to maintain a component's operational stability at accelerated spe ...
,
underclocking Underclocking, also known as downclocking, is modifying a computer or electronic circuit's timing settings to run at a lower clock rate than is specified. Underclocking is used to reduce a computer's power consumption, increase battery life, redu ...
, overvolting, and undervolting, it may be necessary to verify if the new parameters (usually CPU core voltage and
frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in Hertz (unit), hertz (H ...
) are suitable for heavy CPU loads. This is done by running a CPU-intensive program for extended periods of time (usually 24 hours for home PC), to test whether the computer hangs or crashes. CPU stress testing is also referred to as torture testing. Software that is suitable for torture testing should typically run instructions that utilise the entire chip rather than only a few of its units. Stress testing a CPU over the course of 24 hours at 100% load is, in most cases, sufficient to determine that the CPU will function correctly in normal usage scenarios such as in a desktop computer, where CPU usage typically fluctuates at low levels (50% and under). Hardware stress testing and stability are subjective and may vary according to how the system will be used. A stress test for a system running 24/7 or that will perform error sensitive tasks such as
distributed computing A distributed system is a system whose components are located on different computer network, networked computers, which communicate and coordinate their actions by message passing, passing messages to one another from any system. Distributed com ...
or "folding" projects may differ from one that needs to be able to run a single game with reasonably reliability. For example, a comprehensive guide on overclocking Sandy Bridge found that: An engineer at ASUS advised in a 2012 article on
overclocking In computing, overclocking is the practice of increasing the clock rate of a computer to exceed that certified by the manufacturer. Commonly, operating voltage is also increased to maintain a component's operational stability at accelerated spe ...
an
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the devel ...
X79 system, that it is important to choose testing software carefully in order to obtain useful results:


Software commonly used in stress testing

* Aida * IBM Teleprocessing Network Simulator * IBM Workload Simulator * Intel processor diagnostic test * Intel Burn Test * LinX (AVX) * Memtest86+ – memory * OCCT * Passmark Burn-in * Prime95, and derivatives such as HyperPi – CPU/heat * Siege * S&M * Tsung - free software tool


Software

In
software testing Software testing is the act of examining the artifacts and the behavior of the software under test by validation and verification. Software testing can also provide an objective, independent view of the software to allow the business to apprecia ...
, a system stress test refers to tests that put a greater emphasis on robustness,
availability In reliability engineering, the term availability has the following meanings: * The degree to which a system, subsystem or equipment is in a specified operable and committable state at the start of a mission, when the mission is called for at a ...
, and error handling under a heavy load, rather than on what would be considered correct behavior under normal circumstances. In particular, the goals of such tests may be to ensure the software does not crash in conditions of insufficient computational resources (such as
memory Memory is the faculty of the mind by which data or information is Encoding (memory), encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If Foresight (psycholo ...
or disk space), unusually high concurrency, or denial of service attacks. Examples: * A
web server A web server is computer software and underlying Computer hardware, hardware that accepts requests via Hypertext Transfer Protocol, HTTP (the network protocol created to distribute web content) or its secure variant HTTPS. A user agent, c ...
may be stress tested using scripts,
bots The British Overseas Territories (BOTs), also known as the United Kingdom Overseas Territories (UKOTs), are fourteen territories with a constitutional and historical link with the United Kingdom The United Kingdom of Great Britain ...
, and various denial of service tools to observe the performance of a web site during peak loads. These attacks generally are under an hour long, or until a limit in the amount of data that the web server can tolerate is found. Stress testing may be contrasted with load testing: *Load testing examines the entire environment and database, while measuring the response time, whereas stress testing focuses on identified transactions, pushing to a level so as to break transactions or systems. *During stress testing, if transactions are selectively stressed, the database may not experience much load, but the transactions are heavily stressed. On the other hand, during load testing the database experiences a heavy load, while some transactions may not be stressed. *System stress testing, also known as stress testing, is loading the concurrent users over and beyond the level that the system can handle, so it breaks at the weakest link within the entire system.


Critical Infrastructure

Critical infrastructure Critical infrastructure (or critical national infrastructure (CNI) in the UK) is a term used by governments to describe assets that are essential for the functioning of a society and economy – the infrastructure. Most commonly associated wit ...
(CI) such as highways, railways, electric power networks, dams, port facilities, major gas pipelines or oil refineries are exposed to multiple natural and human-induced hazards and stressors, including
earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth Earth is the third planet from the Sun and the only astronomical object ...
s,
landslide Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...
s,
flood A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study o ...
s,
tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a tsunamis in lakes, large lake. Earthquakes, volcanic eruptions and othe ...
,
wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire ...
s,
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate variability and change, Climate change in a broader sense also includes ...
effects or
explosion An explosion is a rapid expansion in volume Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary ...
s. These stressors and abrupt events can cause failures and losses, and hence, can interrupt essential services for the society and the economy. Therefore, CI owners and operators need to identify and quantify the risks posed by the CIs due to different stressors, in order to define mitigation strategies and improve the resilience of the CIs. Stress tests are advanced and standardised tools for hazard and
risk assessment Broadly speaking, a risk assessment is the combined effort of: # identifying and analyzing potential (future) events that may negatively impact individuals, assets, and/or the environment (i.e. hazard analysis); and # making judgments "on the to ...
of CIs, that include both low-probability high-consequence (LP-HC) events and so-called extreme or rare events, as well as the systematic application of these new tools to classes of CI. Stress testing is the process of assessing the ability of a CI to maintain a certain level of functionality under unfavourable conditions, while stress tests consider LP-HC events, which are not always accounted for in the design and risk assessment procedures, commonly adopted by public authorities or industrial stakeholders. A multilevel stress test methodology for CI has been developed in the framework of the European research project STREST, consisting of four phases: Phase 1: ''Preassessment'', during which the data available on the CI (risk context) and on the phenomena of interest (hazard context) are collected. The goal and objectives, the time frame, the stress test level and the total costs of the stress test are defined. Phase 2: ''Assessment'', during which the stress test at the component and the system scope is performed, including fragility and risk analysis of the CIs for the stressors defined in Phase 1. The stress test can result in three outcomes: Pass, Partly Pass and Fail, based on the comparison of the quantified risks to acceptable risk exposure levels and a penalty system. Phase 3: ''Decision'', during which the results of the stress test are analyzed according to the goal and objectives defined in Phase 1. Critical events (events that most likely cause the exceedance of a given level of loss) and risk mitigation strategies are identified. Phase 4: ''Report'', during which the stress test outcome and risk mitigation guidelines based on the findings established in Phase 3 are formulated and presented to the stakeholders. This stress-testing methodology has been demonstrated to six CIs in Europe at component and system level: an oil refinery and petrochemical plant in Milazzo, Italy; a conceptual alpine earth-fill dam in Switzerland; the Baku–Tbilisi–Ceyhan pipeline in Turkey; part of the Gasunie national gas storage and distribution network in the Netherlands; the port infrastructure of Thessaloniki, Greece; and an industrial district in the region of Tuscany, Italy. The outcome of the stress testing included the definition of critical components and events and risk mitigation strategies, which are formulated and reported to stakeholders.


See also

* Burn-in * Destructive testing * Load and performance test tools * Black box testing *
Load testing Load testing is the process of putting demand on a structure or system and measuring its response. Software load testing The term ''load testing'' is used in different ways in the professional software testing community. ''Load testing'' gene ...
* Software performance testing *
Scenario analysis Scenario planning, scenario thinking, scenario analysis, scenario prediction and the scenario method all describe a strategic planning Strategic planning is an organization's business process, process of defining its strategy or direction, and ...
*
Simulation A simulation is the imitation of the operation of a real-world process or system over time. Simulations require the use of Conceptual model, models; the model represents the key characteristics or behaviors of the selected system or proc ...
*
Software testing Software testing is the act of examining the artifacts and the behavior of the software under test by validation and verification. Software testing can also provide an objective, independent view of the software to allow the business to apprecia ...
* White box testing * Technischer Überwachungsverein (TÜV) – product testing and certification * Concurrency testing using the CHESS model checker *
Jinx A jinx (also jynx), in popular superstition and folklore, is a curse or the attribute of attracting bad or negative luck. The word ''"jynx"'' meaning the bird wryneck and sometimes a charm or spell has been in use in English since the seventeent ...
automates stress testing by automatically exploring unlikely execution scenarios. * Highly accelerated life test


References

{{Software testing Software testing Product testing