Parallel Execution

If your computer has more than one CPU or is a multi-core processor, then the scalar dyadic functions ÷, ≥, =, ≤, ⍟, |, !, ○, ∨ and ∧ will, when applied to arrays with a sufficiently large number of elements, execute in parallel in separate system threads.

For example, if you have a computer with 4 cores (either real or virtual) and execute an expression such as (A÷B) where A and/or B contain more than 32,768 elements, then Dyalog will start 4 separate threads, each performing the division on ¼ of the elements of the array(s) and simultaneously creating the corresponding ¼ of the result array. The threads are only started once, and are reused for subsequent multi-threaded operations.

The maximum number of threads to use can be controlled using 1111⌶, and the parallel execution threshold is changed using 1112⌶. These "tuning" I-beams should be considered experimental, and may be changed or replaced in a future release. (See Number of Threads and Parallel Execution Threshold).

Note that these scalar dyadic functions are not multi-threaded when applied to arrays of Boolean or integer values, they are also not multi-threaded for +, - or × when applied to arrays of 64 bits floating (type 645). Tests show that the overhead of preparing such arrays for multi-threaded operations outweigh the performance benefits.