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Probe effect is an unintended alteration in system behavior caused by measuring that system. In code profiling and performance measurements, the delays introduced by insertion or removal of code instrumentation may result in a non-functioning application, or unpredictable behavior.
In electronics, by attaching a multimeter, oscilloscope, or other testing device via a test probe, small amounts of capacitance, resistance, or inductance may be introduced. Though good scopes have very slight effects, in sensitive circuitry these can lead to unexpected failures, or conversely, unexpected fixes to failures.
In debugging of parallel computer programs, sometimes failures (such as deadlocks) are not present when the debugger's code (which was meant to help to find a reason for deadlocks by visualising points of interest in the program code) is attached to the program. This is because additional code changed the timing of the execution of parallel processes, and because of that deadlocks were avoided. [1] This type of bug is known colloquially as a Heisenbug, by analogy with the observer effect in quantum mechanics.
Computer programming is the process of performing particular computations, usually by designing and building executable computer programs. Programming involves tasks such as analysis, generating algorithms, profiling algorithms' accuracy and resource consumption, and the implementation of algorithms. The source code of a program is written in one or more languages that are intelligible to programmers, rather than machine code, which is directly executed by the central processing unit. To produce machine code, the source code must either be compiled or transpiled. Compiling takes the source code from a low-level programming language and converts it into machine code. Transpiling on the other hand, takes the source-code from a high-level programming language and converts it into bytecode. This is interpreted into machine code. The purpose of programming is to find a sequence of instructions that will automate the performance of a task on a computer, often for solving a given problem. Proficient programming thus usually requires expertise in several different subjects, including knowledge of the application domain, specialized algorithms, and formal logic.
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 appreciate and understand the risks of software implementation. Test techniques include, but are not necessarily limited to:
A software bug is an error, flaw or fault in the design, development, or operation of computer software that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. The process of finding and correcting bugs is termed "debugging" and often uses formal techniques or tools to pinpoint bugs. Since the 1950s, some computer systems have been designed to deter, detect or auto-correct various computer bugs during operations.
A logic analyzer is an electronic instrument that captures and displays multiple signals from a digital system or digital circuit. A logic analyzer may convert the captured data into timing diagrams, protocol decodes, state machine traces, opcodes, or may correlate opcodes with source-level software. Logic analyzers have advanced triggering capabilities, and are useful when a user needs to see the timing relationships between many signals in a digital system.
An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is embedded as part of a complete device often including electrical or electronic hardware and mechanical parts. Because an embedded system typically controls physical operations of the machine that it is embedded within, it often has real-time computing constraints. Embedded systems control many devices in common use. In 2009, it was estimated that ninety-eight percent of all microprocessors manufactured were used in embedded systems.
In-circuit emulation (ICE) is the use of a hardware device or in-circuit emulator used to debug the software of an embedded system. It operates by using a processor with the additional ability to support debugging operations, as well as to carry out the main function of the system. Particularly for older systems, with limited processors, this usually involved replacing the processor temporarily with a hardware emulator: a more powerful although more expensive version. It was historically in the form of bond-out processor which has many internal signals brought out for the purpose of debugging. These signals provide information about the state of the processor.
Test-driven development (TDD) is a software development process relying on software requirements being converted to test cases before software is fully developed, and tracking all software development by repeatedly testing the software against all test cases. This is as opposed to software being developed first and test cases created later.
A programming tool or software development tool is a computer program that software developers use to create, debug, maintain, or otherwise support other programs and applications. The term usually refers to relatively simple programs, that can be combined to accomplish a task, much as one might use multiple hands to fix a physical object. The most basic tools are a source code editor and a compiler or interpreter, which are used ubiquitously and continuously. Other tools are used more or less depending on the language, development methodology, and individual engineer, often used for a discrete task, like a debugger or profiler. Tools may be discrete programs, executed separately – often from the command line – or may be parts of a single large program, called an integrated development environment (IDE). In many cases, particularly for simpler use, simple ad hoc techniques are used instead of a tool, such as print debugging instead of using a debugger, manual timing instead of a profiler, or tracking bugs in a text file or spreadsheet instead of a bug tracking system.
JTAG is an industry standard for verifying designs and testing printed circuit boards after manufacture.
In computing, a POST card is a plug-in diagnostic interface card that displays progress and error codes generated during power-on self-test (POST) of a computer. It is used to troubleshoot computers that do not start up.
In computer science, concurrency is the ability of different parts or units of a program, algorithm, or problem to be executed out-of-order or in partial order, without affecting the outcome. This allows for parallel execution of the concurrent units, which can significantly improve overall speed of the execution in multi-processor and multi-core systems. In more technical terms, concurrency refers to the decomposability of a program, algorithm, or problem into order-independent or partially-ordered components or units of computation.
Observer effect, observer bias, observation effect, or observation bias may refer to a number of concepts, some of them closely related:
In integrated circuit design, hardware emulation is the process of imitating the behavior of one or more pieces of hardware with another piece of hardware, typically a special purpose emulation system. The emulation model is usually based on a hardware description language source code, which is compiled into the format used by emulation system. The goal is normally debugging and functional verification of the system being designed. Often an emulator is fast enough to be plugged into a working target system in place of a yet-to-be-built chip, so the whole system can be debugged with live data. This is a specific case of in-circuit emulation.
In computer programming jargon, a heisenbug is a software bug that seems to disappear or alter its behavior when one attempts to study it. The term is a pun on the name of Werner Heisenberg, the physicist who first asserted the observer effect of quantum mechanics, which states that the act of observing a system inevitably alters its state. In electronics, the traditional term is probe effect, where attaching a test probe to a device changes its behavior.
In computer science, event monitoring is the process of collecting, analyzing, and signaling event occurrences to subscribers such as operating system processes, active database rules as well as human operators. These event occurrences may stem from arbitrary sources in both software or hardware such as operating systems, database management systems, application software and processors. Event monitoring may use a time series database.
Dynamic program analysis is analysis of computer software that involves executing the program in question. Dynamic program analysis includes familiar techniques from software engineering such as unit testing, debugging, and measuring code coverage, but also includes lesser-known techniques like program slicing and invariant inference. Dynamic program analysis is widely applied in security in the form of runtime memory error detection, fuzzing, dynamic symbolic execution, and taint tracking.
Stress testing is a software testing activity that determines the robustness of software by testing beyond the limits of normal operation. Stress testing is particularly important for "mission critical" software, but is used for all types of software. Stress tests commonly put a greater emphasis on robustness, availability, and error handling under a heavy load, than on what would be considered correct behavior under normal circumstances.
In computer programming and software development, debugging is the process of finding and resolving bugs within computer programs, software, or systems.
In computer science, robustness is the ability of a computer system to cope with errors during execution and cope with erroneous input. Robustness can encompass many areas of computer science, such as robust programming, robust machine learning, and Robust Security Network. Formal techniques, such as fuzz testing, are essential to showing robustness since this type of testing involves invalid or unexpected inputs. Alternatively, fault injection can be used to test robustness. Various commercial products perform robustness testing of software analysis.
High performance computing applications run on massively parallel supercomputers consist of concurrent programs designed using multi-threaded, multi-process models. The applications may consist of various constructs with varying degree of parallelism. Although high performance concurrent programs use similar design patterns, models and principles as that of sequential programs, unlike sequential programs, they typically demonstrate non-deterministic behavior. The probability of bugs increases with the number of interactions between the various parallel constructs. Race conditions, data races, deadlocks, missed signals and live lock are common error types.