Gather

Syntax

gather[elements,root]

Semantics

Gather a number of elements (equal to elements) from each process and send these to the root process.

Example

var x:array[Int,12] :: allocated[single[on[2]]];
var r:array[Int,3] :: allocated[multiple[]];
var p;
par p from 0 to 3
{
   (x::gather[3,2]):=r;
};

In this example, the variable x is allocated on the root process (2) only. Whereas r is allocated on all processes. In the assignment all three elements of r are gathered from each process and sent to the root process (2) and then placed into variable x in the order defined by the source's PID.