hot spot
    n 1: a place of political unrest and potential violence; "the
         United States cannot police all of the world's hot spots"
         [syn: hot spot, hotspot]
    2: a point of relatively intense heat or radiation [syn: hot
       spot, hotspot]
    3: a lively entertainment spot [syn: hot spot, hotspot]

hot spot
 n.

    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 optimization 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, 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 gestures, which trigger some
    action. World Wide Web pages now provide the canonical examples; WWW
    browsers present hypertext links as hot spots which, when clicked on, point
    the browser at another document (these are specifically called hotlinks).

    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.

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)