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In computer science, garbage collection (GC) is a form of automatic memory management. The ''garbage collector'', or just ''collector'', attempts to reclaim ''garbage'', or memory occupied by objects that are no longer in use by the program. Garbage collection was invented by John McCarthy around 1959 to abstract away manual memory management in Lisp.〔(【引用サイトリンク】title=Recursive functions of symbolic expressions and their computation by machine, Part I )〕〔(【引用サイトリンク】title=Recursive functions of symbolic expressions and their computation by machine, Part I )〕 Garbage collection is often portrayed as the opposite of manual memory management, which requires the programmer to specify which objects to deallocate and return to the memory system. However, many systems use a combination of approaches, including other techniques such as stack allocation and region inference. Like other memory management techniques, garbage collection may take a significant proportion of total processing time in a program and, as a result, can have significant influence on performance. Resources other than memory, such as network sockets, database handles, user interaction windows, and file and device descriptors, are not typically handled by garbage collection. Methods used to manage such resources, particularly destructors, may suffice to manage memory as well, leaving no need for GC. Some GC systems allow such other resources to be associated with a region of memory that, when collected, causes the other resource to be reclaimed; this is called ''finalization''. Finalization may introduce complications limiting its usability, such as intolerable latency between disuse and reclaim of especially limited resources, or a lack of control over which thread performs the work of reclaiming. == Principles == The basic principles of garbage collection are to find data objects in a program that cannot be accessed in the future, and to reclaim the resources used by those objects. Many programming languages require garbage collection, either as part of the language specification (for example, Java, C#, D language, Go and most scripting languages) or effectively for practical implementation (for example, formal languages like lambda calculus); these are said to be ''garbage collected languages''. Other languages were designed for use with manual memory management, but have garbage-collected implementations available (for example, C and C++). Some languages, like Ada, Modula-3, and C++/CLI, allow both garbage collection and manual memory management to co-exist in the same application by using separate heaps for collected and manually managed objects; others, like D, are garbage-collected but allow the user to manually delete objects and also entirely disable garbage collection when speed is required. While integrating garbage collection into the language's compiler and runtime system enables a much wider choice of methods, ''post-hoc'' GC systems exist, such as ARC, including some that do not require recompilation. (''Post-hoc'' GC is sometimes distinguished as ''litter collection''.) The garbage collector will almost always be closely integrated with the memory allocator. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Garbage collection (computer science)」の詳細全文を読む スポンサード リンク
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