First time using Parallel

[rikki cattermole]

On 27/12/2021 12:10 AM, max haughton wrote:
> I would start by removing the use of stdout in your loop kernel - I'm 
> not familiar with what you are calculating, but if you can basically 
> have the (parallel) loop operate from (say) one array directly into 
> another then you can get extremely good parallel scaling with almost no 
> effort.
> 
> Not using in the actual loop should make the code faster even without 
> threads because having a function call in the hot code will mean 
> compilers optimizer will give up on certain transformations - i.e. do 
> all the work as compactly as possible then output the data in one step 
> at the end.

It'll speed it up significantly.

Standard IO has locks in it. So you end up with all calculations 
grinding to a half waiting for another thread to finish doing something.