An abnormal end or abend is an abnormal termination of software, or a program crash. This usage derives from an error message from the IBM OS/360, IBM zOS operating systems. Usually capitalized, but may appear as "abend". The most common were ABEND 0C7 (Data exception) and ABEND 0CB (Division by zero).
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For example, in k-means clustering algorithm, allowing only 5% loss in classification accuracy can provide 50 times energy saving compared to the fully accurate classification. The key requirement in approximate computing is that approximation can be introduced only in non- critical data, since approximating critical data (e.g., control operations) can lead to disastrous consequences, such as program crash or erroneous output.
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An implicit test oracle relies on implied information and assumptions. For example, there may be some implied conclusion from a program crash, i.e. unwanted behaviour - an oracle to determine that there may be a problem. There are a number of ways to search and test for unwanted behaviour, whether some call it negative testing, where there are specialized subsets such as fuzzing.
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Relying on these implementation details makes the software non-portable, however portability may not be a concern if the software is not supposed to be used outside of a specific runtime. Undefined behavior can result in a program crash or even in failures that are harder to detect and make the program look like it is working normally, such as silent loss of data and production of incorrect results.
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In 1974, GM offered driver and passenger airbags as optional equipment on large Cadillacs, Buicks, and Oldsmobiles. In 1979, NHTSA began crash-testing popular cars and publishing the results, to inform consumers and encourage manufacturers to improve the safety of their vehicles. Initially, the US NCAP (New Car Assessment Program) crash tests examined compliance with the occupant-protection provisions of FMVSS 208. Over the subsequent years, this NHTSA program was gradually expanded in scope.
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The tool is named after Doctor Watson of Sherlock Holmes fame, the idea being that it would collect error information (symptoms) following a program crash. The use of the word "Watson" has since been expanded to include general end-user feedback services. The original name of this diagnostic tool was "Sherlock". The information obtained and logged by Dr. Watson is the information needed by technical support personnel to diagnose a program error for a computer running Windows.
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Memory corruption occurs in a computer program when the contents of a memory location are modified due to programmatic behavior that exceeds the intention of the original programmer or program/language constructs; this is termed violating memory safety. The most likely cause of memory corruption is programming error. When the corrupted memory contents are used later in that program, it leads either to program crash or to strange and bizarre program behavior. Nearly 10% of application crashes on Windows systems are due to heap corruption.
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In the case of computing, concrete, precise information is in general not computable within finite time and memory (see Rice's theorem and the halting problem). Abstraction is used to allow for generalized answers to questions (for example, answering "maybe" to a yes/no question, meaning "yes or no", when we (an algorithm of abstract interpretation) cannot compute the precise answer with certainty); this simplifies the problems, making them amenable to automatic solutions. One crucial requirement is to add enough vagueness so as to make problems manageable while still retaining enough precision for answering the important questions (such as "might the program crash?").
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If such a pointer is a null pointer, dangling pointer (pointing to memory that has already been freed), or to a memory location outside of current stack or heap bounds, it is referring to memory that is not then possessed by the program. Using such pointers is a serious programming flaw. Accessing such memory usually causes operating system exceptions, that most commonly lead to a program crash (unless suitable memory protection software is being used). #Using memory beyond the memory that was allocated (buffer overflow): If an array is used in a loop, with incorrect terminating condition, memory beyond the array bounds may be accidentally manipulated.
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In software, a stack overflow occurs if the call stack pointer exceeds the stack bound. The call stack may consist of a limited amount of address space, often determined at the start of the program. The size of the call stack depends on many factors, including the programming language, machine architecture, multi-threading, and amount of available memory. When a program attempts to use more space than is available on the call stack (that is, when it attempts to access memory beyond the call stack's bounds, which is essentially a buffer overflow), the stack is said to overflow, typically resulting in a program crash.
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The ability to detect non-fatal errors is a major distinction between PurifyPlus and similar programs from the usual debuggers. By contrast, debuggers generally only allow the programmer to quickly find the sources of fatal errors, such as a program crash due to dereferencing a null pointer, but do not help to detect the non-fatal memory errors. Debuggers are useful for other things that PurifyPlus is not intended for, such as for stepping through the code line by line or examining the program's memory by hand at a particular moment of execution. In other words, these tools can complement each other for a skilled developer.
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Traffic lights can have both positive and negative effects on traffic safety and traffic flow. The separation of conflicting streams of traffic in time can reduce the chances of right-angle collisions by turning traffic and cross traffic, but they can increase the frequency of rear-end crashes by up to 50%.National Cooperative Highway Research Program, Crash Reduction Factors for Traffic Engineering and Intelligent Transportation System (ITS) Improvements: State-of-Knowledge Report, November 2005, Table 3 Since right-angled and turn-against-traffic collisions are more likely to result in injuries, this is often an acceptable trade-off. They can also adversely affect the safety of bicycle and pedestrian traffic.
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Software developers also responded by devising a recovery method which became a standard feature of many commercial programs. They accept an "asterisk parameter", an asterisk (star) character typed following the program name when the program is run from the TRSDOS Ready prompt. When used following a spontaneous reboot (or an accidental reset, program crash, or exit to TRSDOS without saving data to disk), the program loads without initializing its data area(s), preserving any program data still present from the pre-reboot session. Thus, for example, if a VisiCalc user suffers a spontaneous reboot, to recover data the user enters at TRSDOS Ready, and Visicalc restores the previous computing session intact.
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Object resurrection occurs via the following process. First, an object becomes garbage when it is no longer reachable from the program, and may be collected (destroyed and deallocated). Then, during object destruction, before the garbage collector deallocates the object, a finalizer method may be run, which may in turn make that object or another garbage object (reachable from the object with a finalizer) reachable again by creating references to it, as a finalizer may contain arbitrary code. If this happens, the referenced object – which is not necessarily the finalized object – is no longer garbage, and cannot be deallocated, as otherwise the references to it would become dangling references and cause errors when used, generally program crash or unpredictable behavior.
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Flip-flops are subject to a problem called metastability, which can happen when two inputs, such as data and clock or clock and reset, are changing at about the same time. When the order is not clear, within appropriate timing constraints, the result is that the output may behave unpredictably, taking many times longer than normal to settle to one state or the other, or even oscillating several times before settling. Theoretically, the time to settle down is not bounded. In a computer system, this metastability can cause corruption of data or a program crash if the state is not stable before another circuit uses its value; in particular, if two different logical paths use the output of a flip-flop, one path can interpret it as a 0 and the other as a 1 when it has not resolved to stable state, putting the machine into an inconsistent state.
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