hot spot n.
A region in a gene in which there is a high rate of mutation. Its existence depends on the size of the region concerned, the readiness with which the mutation can be detected, and the possibility that selection against mutants at that point is less than that against mutants elsewhere.
| hot spot A volcanic area that forms as a tectonic plate moves over a point heated from deep within the Earth's mantle. The source of the heat is thought to be the decay of radioactive elements. The Hawaiian Islands formed as a series of hot spots. See more at tectonic boundary. |
A place deep within the Earth where hot magma rises to just underneath the surface, creating a bulge and volcanic activity (see volcano). The chain of Hawaiian Islands (see Hawaii) is thought to have been created by the movement of a tectonic plate over a hot spot.
1. (primarily used by C/Unix programmers, but spreading) It is received wisdom that in most programs, less than 10% of the code eats 90% of the execution time; if one were to graph instruction visits versus code addresses, one would typically see a few huge spikes amidst a lot of low-level noise. Such spikes are called "hot spots" and are good candidates for heavy optimisation or hand-hacking. The term is especially used of tight loops and recursions in the code's central algorithm, as opposed to (say) initial set-up costs or large but infrequent I/O operations.
See tune, bum, hand-hacking.
2. The active location of a cursor on a bit-map display. "Put the mouse's hot spot on the "ON" widget and click the left button."
3. A screen region that is sensitive to mouse clicks, which trigger some action. Hypertext help screens are an example, in which a hot spot exists in the vicinity of any word for which additional material is available.
4. In a massively parallel computer with shared memory, the one location that all 10,000 processors are trying to read or write at once (perhaps because they are all doing a busy-wait on the same lock).
5. More generally, any place in a hardware design that turns into a performance bottleneck due to resource contention.
6. wireless hotspot.
[Jargon File]
(1995-02-16)