To move wildly or violently, without accomplishing anything useful. Paging or swapping systems that are overloaded waste most of their time moving data into and out of core (rather than performing useful computation) and are therefore said to thrash. Thrashing can also occur in a cache due to cache conflict or in a multiprocessor (see ping-pong).

Someone who keeps changing his mind (especially about what to work on next) is said to be thrashing. A person frantically trying to execute too many tasks at once (and not spending enough time on any single task) may also be described as thrashing.

Compare multitask.

[Jargon File]




1. See multithreading.

2. See threaded code.

3. topic thread.

[Jargon File]



threaded code


A technique for implementing virtual machine interpreters, introduced by J.R. Bell in 1973, where each op-code in the virtual machine instruction set is the address of some (lower level) code to perform the required operation. This kind of virtual machine can be implemented efficiently in machine code on most processors by simply performing an indirect jump to the address which is the next instruction.

Many Forth implementations use threaded code and nowadays some use the term "threading" for almost any technique used to implement Forth's virtual machine.

["James R. Bell", "Threaded Code", CACM, 1973, 16, 6, pp 370-372].

["An Architectural Trail to Threaded Code Systems", Kogge, P. M., IEEE Computer, March 1982].

Last updated: 1998-09-02



Thread Language Zero


(TL0) The instruction set of the TAM (Threaded Abstract Machine), used to implement Id.

["Fine-grain Parallelism with Minimal Hardware Support", David Culler et al, SIGPLAN Notices 26(4):164-175, ASPLOS-IV Proc, Apr 1991].

Last updated: 1995-03-13



A description of code which is either re-entrant or protected from multiple simultaneous execution by some form of mutual exclusion.

Last updated: 1997-01-30

three-finger salute

Vulcan nerve pinch

three-letter acronym


(TLA) The canonical, self-describing acronym for the name of a species with which computing terminology is infested. Examples include MCA, FTP, SNA, CPU, MMU, DMU, FPU, TLA.

This dictionary contains many TLAs.

Sometimes used by extension for any confusing acronym. People who like this looser usage argue that not all TLAs have three letters, just as not all four-letter words have four letters. One also hears of "ETLA" (Extended Three-Letter Acronym) being used to describe four-letter acronyms. The term "SFLA" (Stupid Four-Letter Acronym) has also been reported.

See also YABA.

The self-effacing phrase "TDM TLA" (Too Damn Many...) is used to bemoan the plethora of TLAs in use. In 1989, a random of the journalistic persuasion asked hacker Paul Boutin "What do you think will be the biggest problem in computing in the 90s?" Paul's straight-faced response: "There are only 17,000 three-letter acronyms." (To be exact, there are 26^3 = 17,576.)

Last updated: 2014-08-14



A client-server architecture in which the user interface, functional process logic ("business rules") and data storage and access are developed and maintained as independent modules, most often on separate platforms.

Apart from the usual advantages of modular software with well defined interfaces, the three-tier architecture is intended to allow any of the three tiers to be upgraded or replaced independently as requirements or technology change. For example, an upgrade of desktop operating system from Microsoft Windows to Unix would only affect the user interface code.

Typically, the user interface runs on a desktop PC or workstation and uses a standard graphical user interface, functional process logic may consist of one or more separate modules running on a workstation or application server, and an RDBMS on a database server or mainframe contains the data storage logic. The middle tier may be multi-tiered itself (in which case the overall architecture is called an "n-tier architecture").

Last updated: 1998-05-13


1. The rate at which a processor can work expressed in instructions per second or jobs per hour or some other unit of performance.


2. data transfer rate.

Last updated: 2001-05-22

Nearby terms:

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