Information about Crash (computing)
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A public payphone that has failed and is displaying the Blue Screen of Death.
A crash in computing is a condition where a program (either an application or part of the operating system) stops performing its expected function and also stops responding to other parts of the system. Often the offending program may simply appear to freeze. If this program is a critical part of the operating system kernel the entire computer may crash (a system crash).
Many crashes are the result of the execution of a single machine instruction, but the causes of this are many fold. Typical causes are when the program counter is set to an incorrect address or a buffer overflow overwrites a portion of program code due to an earlier bug. In either case, it is quite common for the processor to attempt to execute data or random memory values. Since all data values are possible but only some values are valid instructions, this often results in an illegal instruction exception. By chance such data or random values could be valid (though unplanned) instructions. If while successfully executing such instructions the processor happens onto a branch instruction that moves the program counter back a few bytes it would simply repeat those few instructions over and over, being stuck in an endless loop. One might say that the original bug that upset the program counter "caused" the crash, but the actual fault was an illegal instruction or endless loop some time later. The art of debugging such crashes is connecting the actual cause of the crash (easily determined) with the code that set off the chain of events. This is often very far from obvious—the original bug is usually perfectly valid code from the processor's perspective.
On earlier personal computers, it was actually possible to cause hardware damage through trying to write to hardware addresses outside of the system's main memory. Occasionally, execution of arbitrary data on a system will result in a breakup of screen display. This is widely considered a severe system crash.
Another cause of crashes is a race condition in communication between processes. One process may send a signal to a second process then stop execution until it receives a response. If the second process is busy the signal will be forced to wait until the process can get to it. However, if the second process was busy sending a signal to the first process then both processes would wait forever for the other to respond to signals and never see the other’s signal. If the processes are uninterruptible they will hang and have to be shut down. If at least one of the processes is a critical kernel process the whole system may crash and have to be restarted.
Etymology
The term "crash" may originate in the phrase "head crash" which would occur when the read/write heads in a hard disk would physically come into contact with (i.e. crash into) the disk surface. The result of this would usually be that the computer would freeze up.Application crashes
An application typically crashes when it performs an operation which is not allowed by the operating system. The operating system then shuts down the application.Typical errors that result in application crashes include:
- attempting to read or write memory that is not allocated for reading or writing by that application (general protection fault)
- attempting to execute privileged or invalid instructions
- unforeseen circumstances or poor code writing that results in the program executing an endless loop
- attempting to perform I/O operations on hardware devices to which it does not have permission to access
- passing invalid arguments to system calls
- attempting to access other system resources to which the application does not have permission to access (bus error)
Website server crashes
The software running the server behind a website may crash, rendering it inaccessible entirely or providing only an error message instead of normal content.Operating system crashes
An operating system crash commonly occurs when an hardware exception occurs that cannot be handled. Operating system crashes can also occur when internal sanity-checking logic within the operating system detects that the operating system has lost its internal self-consistency.In an ideal world, well-written operating systems would always remain stable even when individual applications crash. Vendors such as Microsoft and Apple frequently market their operating systems as being intrinsically crash-resistant such that should an application crash the operating system remains unharmed.
See also
- Black screen of death
- Blue Screen of Death
- Crash to Desktop
- Safe Mode
- Debugging
- Kernel panic
- Reboot
- Recovery
- Crash reporter
- Data loss
computing is synonymous with counting and calculating. Originally, people that performed these functions were known as computers. Today it refers to a science and technology that deals with the computation and the manipulation of symbols.
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Application software is a subclass of computer software that employs the capabilities of a computer directly and thoroughly to a task that the user wishes to perform. This should be contrasted with system software which is involved in integrating a computer's various capabilities,
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An operating system (OS) is the software that manages the sharing of the resources of a computer. An operating system processes system data and user input, and responds by allocating and managing tasks and internal system resources as a service to users and programs of the
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This article is about the computer malfunction called hanging. For the capital punishment, see hanging. For other uses, see Hang (computing) (disambiguation).
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kernel is the central component of most computer operating systems (OS). Its responsibilities include managing the system's resources (the communication between hardware and software components).
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instruction is a single operation of a processor defined by an instruction set architecture. In a broader sense, an "instruction" may be any representation of an element of an executable program, such as a bytecode.
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The program counter (also called the instruction pointer, part of the instruction sequencer in some computers) is a register in a computer processor which indicates where the computer is in its instruction sequence.
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buffer overflow, or buffer overrun, is a programming error which may result in a memory access exception and program termination, or in the event of the user being malicious, a possible breach of system security.
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A software bug (or just "bug") is an error, flaw, mistake, failure, or fault in a computer program that prevents it from behaving as intended (e.g., producing an incorrect result).
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central processing unit (CPU), or sometimes simply processor, is the component in a digital computer capable of executing a program.(Knott 1974) It interprets computer program instructions and processes data.
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Endless Loop is the second EP by Japanese singer Eiko Shimamiya.
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Track listing
- 求道の人 (Lyrics and music by Eiko Shimamiya/Arranged by Seiichi Kyoda)
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Debugging is a methodical process of finding and reducing the number of bugs, or defects, in a computer program or a piece of electronic hardware thus making it behave as expected.
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A race condition or race hazard is a flaw in a system or process whereby the output of the process is unexpectedly and critically dependent on the sequence or timing of other events.
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In computing, a process is an instance of a computer program that is being sequentially executed.[1] While a program itself is just a passive collection of instructions, a process is the actual execution of those instructions.
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signal is a limited form of inter-process communication used in Unix, Unix-like, and other POSIX-compliant operating systems. Essentially it is an asynchronous notification sent to a process in order to notify it of an event that occurred.
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uninterruptible (woken explicitly). An uninterruptible sleep state is a sleep state that cannot handle a signal (such as waiting for disk or network IO (input/output)).
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The word hang or hanging can mean:
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- As in: "hang on a second also" and similar = "wait a second"
- Hanging, a form of capital punishment.
- Hang (musical instrument), a metallic drum.
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kernel is the central component of most computer operating systems (OS). Its responsibilities include managing the system's resources (the communication between hardware and software components).
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A head crash is a specific type of hard disk failure, and occurs when the read-write head of a hard disk drive touches its rotating platter resulting in catastrophic damage to the magnetic media on the platter surface (see Hard disk platter).
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Disk read/write heads are mechanisms that read data from or write data to disk drives. The heads have gone through a number of changes over the years.
In a hard drive, the heads 'fly' above the disk surface with clearance of as little as 3 nanometres.
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In a hard drive, the heads 'fly' above the disk surface with clearance of as little as 3 nanometres.
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Hard disk drive
An IBM hard disk drive with the metal cover removed. The platters are highly reflective.
Date Invented: September 13 1956
Invented By: An IBM team led by Reynold Johnson
Connects to:
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An IBM hard disk drive with the metal cover removed. The platters are highly reflective.
Date Invented: September 13 1956
Invented By: An IBM team led by Reynold Johnson
Connects to:
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Application software is a subclass of computer software that employs the capabilities of a computer directly and thoroughly to a task that the user wishes to perform. This should be contrasted with system software which is involved in integrating a computer's various capabilities,
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- This article is about the error. For the webcomic, see General Protection Fault (comic).
A General Protection Fault (GPF) in the Intel x86 and AMD x86-64 architectures, and other unrelated architectures is a fault (a type of an interrupt) which can
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Endless Loop is the second EP by Japanese singer Eiko Shimamiya.
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Track listing
- 求道の人 (Lyrics and music by Eiko Shimamiya/Arranged by Seiichi Kyoda)
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Hardware is a general term that refers to the physical artifacts of a technology.It may also mean the physical components of a computer system.
Hardware historically meant the metal parts and fittings that were used to make wooden products stronger, more functional, longer
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Hardware historically meant the metal parts and fittings that were used to make wooden products stronger, more functional, longer
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In computing, a bus error is generally an attempt to access memory that the CPU cannot physically address. Bus errors can also be caused by any general device fault that the computer detects.
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web server can mean one of two things:
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- A computer program that is responsible for accepting HTTP requests from clients, which are known as web browsers, and serving them HTTP responses along with optional data contents, which usually are web pages such as HTML documents and
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A website (alternatively, Web site or web site) is a collection of Web pages, images, videos or other digital assets that is hosted on one or several Web server(s), usually accessible via the Internet, cell phone or a LAN.
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Exception handling is a programming language construct or computer hardware mechanism designed to handle the occurrence of some condition that changes the normal flow of execution. The condition is called an exception.
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In computer science, a subroutine (function, method, procedure, or subprogram) is a portion of code within a larger program, which performs a specific task and can be relatively independent of the remaining code.
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