The difference between concurrency and parallelism

Note: Reprint source http://www.cnblogs.com/taven/archive/2012/06/07/2540561.html

Concurrent English is Concurrency, parallel English is Parallel, concurrency and parallelism are two different concepts.

Parallelism means that at the same time, multiple instructions are executed simultaneously on multiple processors.

Concurrency means that at the same time, only one instruction can be executed, but multiple process instructions are executed quickly, making it possible to have multiple processes concurrently executing at the macro level.

Someone has done a metaphor, to complete the task of eating three steamed bread, a person can take a bite of this steamed bread, the steamed bread bite, so alternately, finally eat three steamed bread, this isconcurrent, because in three steamed bread on the same time the eating behavior occurred.

Three steamed bread if divided to three people to eat, such a task to complete the form called parallel.

The difference between concurrency and parallelism