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garbageabetical order

1. The result of using an insertion sort to merge data into an unsorted list.

2. The state of any file or list that is supposed to be sorted, but is not.

Last updated: 1997-02-11

garbage collect

(GC) The process by which dynamically allocated storage is reclaimed during the execution of a program. The term usually refers to automatic periodic storage reclamation by the garbage collector (part of the run-time system), as opposed to explicit code to free specific blocks of memory.

Automatic garbage collection is usually triggered during memory allocation when the amount free memory falls below some threshold or after a certain number of allocations. Normal execution is suspended and the garbage collector is run. There are many variations on this basic scheme.

Languages like Lisp represent expressions as graphs built from cells which contain pointers and data. These languages use automatic dynamic storage allocation to build expressions. During the evaluation of an expression it is necessary to reclaim space which is used by subexpressions but which is no longer pointed to by anything. This reclaimed memory is returned to the free memory pool for subsequent reallocation.

Without garbage collection the program's memory requirements would increase monotonically throughout execution, possibly exceeding system limits on virtual memory size.

The three main methods are mark-sweep garbage collection, reference counting and copying garbage collection.

See also the AI koan about garbage collection.

Last updated: 1997-08-25

Garbage In, Garbage Out

<humour>

(GIGO) /gi:'goh/ Wilf Hey's maxim expressing the fact that computers, unlike humans, will unquestioningly process nonsensical input data and produce nonsensical output. Of course a properly written program will reject input data that is obviously erroneous but such checking is not always easy to specify and is tedious to write.

GIGO is usually said in response to lusers who complain that a program didn't "do the right thing" when given imperfect input or otherwise mistreated in some way. Also commonly used to describe failures in human decision making due to faulty, incomplete, or imprecise data.

The expansion "Garbage In, Gospel Out" is an ironic comment on the tendency to put excessive trust in "computerised" data.

[Jargon File]

Last updated: 2004-10-03

Nearby terms:

GAPLog ♦ garbageabetical order ♦ garbage collect ♦ garbage collection

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