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In a graph, an edge is a connection between two nodes.
In a directed graph (digraph), edges have a direction; otherwise the start and end nodes are interchangeable. By convention, two directed edges between the same two nodes, but in different directions, are depicted as a bi-directional edge.
Typically an edge represents some relation between nodes.
Relevance to memory management: In memory management, edges normally represent the fact that an object holds a reference to another object.
See also: graph.
An entry table is a table of references into a set of objects used to indirect references from the outside.
The Lieberman-Hewitt collector(1) represented references from older generations to younger ones by indirect pointers through an entry table in the younger generation that contained the actual address of the young object. This is fairly expensive without special hardware; other generational collectors generally use remembered sets.
See also: generational garbage collection; exit table.
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An entry table is an implementation of a remembered set, where, for a given generation, there is a list of objects in older generations which contain references into that generation.
One could also store the actual locations of the references, which would save time when scanning, but incur other costs.
Similar terms: remembered set.
See also: generational garbage collection;
exit table.
Garbage collection is exact (or precise) if it deals only with exact references.
An exact collector(1) needs to know the format of the objects and the roots, so that it can tell which fields are references.
Opposites: conservative garbage collection.
An exact or precise or sure reference is a value the collector(1) knows is a reference.
This is the usual sort of reference. The term is used to draw a contrast with ambiguous reference.
Opposites: ambiguous reference.
An exact or precise root is a root that contains only exact references.
Opposites: ambiguous root.
See also: exact reference.
A segregated fit allocation mechanism which has a separate free list for each possible block size. The array of free lists may be represented sparsely. Large blocks may be treated separately.
See also: segregated fit; segregated free list; allocation mechanism.
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A stack that stores activation records, particularly subroutine return information, is known as a control stack.
An exit table is a table of all references from a set of objects to objects outside the set.
See also: entry table(1); entry table(2).
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The lifetime or extent of an object is the time for which the object is live.
External fragmentation is the inability to use memory(1) because free(3) memory is divided into many small blocks.
If live objects are scattered, the free blocks cannot be coalesced, and hence no large blocks can be allocated.
Common solutions to external fragmentation include:
See also: internal fragmentation.
Related publications: