In computer science, thrash is the poor performance of a virtual memory (or paging) system, when the same pages are being loaded repeatedly due to a lack of main memory. Depending on the configuration and algorithm, the real throughput of a system can degrade by multiple orders of magnitude. Thrashing arises from programs or workloads that present insufficient locality of reference; if the working set of a program or a workload cannot be effectively held within the main memory, then constant data swapping, i.e., thrashing, will occur. Originally thrashing describes the phenomenon that data is constantly being swapped between main memory and hard disk, thus making sounds due to continuous disk heads moving. Computer science is the study of information and computation. ... The memory pages of the virtual address space seen by the process, may reside non-contiguously in primary, or even secondary storage. ... In computer operating systems, paging memory allocation algorithms divide computer memory into small partitions, and allocates memory using a page as the smallest building block. ... In computer operating systems, paging memory allocation algorithms divide computer memory into small partitions, and allocates memory using a page as the smallest building block. ... Primary storage is a category of computer storage, often called main memory. ... An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. ... In computer science, locality of reference, sometimes also called the principle of locality, is a concept which deals with the process of accessing a single resource multiple times. ... Working set is the set of virtual memory pages currently used by the process. ...

The term is also more generally used when a small set of faster storage space used to speed up access to a large set of slower storage space is accessed in a way that cancels out any benefits from the faster storage. An example for this is cache trashing where main memory is accessed in a pattern that leads to multiple main memory locations competing for the same cache lines, which results in excessive cache misses.

In software testing, thrashing means to extensively test a software system, giving a program various inputs and observing the behavior and outputs of the program. Software Testing is a process used to help identify the correctness, completeness, security and quality of developed computer software. ...

Reference

• M. Morris Mano and Charles R. Kim, "Logic and Computer Design Fundamentals", pp. 622.
• P. J. Denning. 1968. Thrashing: Its Causes and Prevention. Proceedings AFIPS,1968 Fall Joint Computer Conference, vol. 33, pp. 915-922.