chemical reaction

n : (chemistry) a process in which one or more substances are

changed into others; "there was a chemical reaction of

the lime with the ground water" [syn: {reaction}]

critical section

A non-{re-entrant} piece of code that can only be executed by

one process at a time. It will usually terminate in bounded

time and a process will only have to wait a bounded time to

enter it. Some synchronisation mechanism is required at the

entry and exit of the critical section to ensure exclusive

use.