On 09/01/2017 07:27 AM, Brian wrote:
double [] hugeCalc(int i){
// Code that takes a long time
}
so if I do
double[][int] _hugeCalcCache;
foreach(i ; I)
_hugeCalcCache[i] = hugeCalc(i);
of course the required time is I.length * (a long time), so I wanted to
shorten this by splitting to different threads :
foreach(i ; parallel(I) )
_hugeCalcCache[i] = hugeCalc(i);
but as you can guess, it doesn't work that easily.
Works pretty well for me:
----
double [] hugeCalc(int i)
{
// Code that takes a long time
import core.thread: Thread;
import std.datetime: seconds;
Thread.sleep(1.seconds);
return [i];
}
void main()
{
static import std.range;
import std.parallelism: parallel;
auto I = std.range.iota(0, 10);
double[][int] _hugeCalcCache;
foreach(i ; parallel(I))
_hugeCalcCache[i] = hugeCalc(i);
}
----
That runs in about 3 seconds here. The serial version would of course
take about 10 seconds. So, parallelism achieved!
Though I don't know if it's safe to access an associative array
concurrently like that. I'd use a normal dynamic array instead and
initialize it before going parallel:
----
auto _hugeCalcCache = new double[][](10);
----
