More threads -> Slower program ??

[Yuxuan Shui via Digitalmars-d-learn]

On Wednesday, 12 August 2015 at 23:15:48 UTC, Adam D. Ruppe wrote:
> On Wednesday, 12 August 2015 at 23:06:32 UTC, Yuxuan Shui wrote:
>> What is wrong here?
>
> I didn't look too closely, but there's some memory allocations 
> going on there which have the potential of locking all the 
> threads any time one of them tries to allocate.
>
> Parallelism's benefits are largely erased by the memory 
> allocator lock and can be set back by the cache being 
> invalidated as it jumps around that allocated memory, so you 
> generally want to make sure the threads are doing work on local 
> variables only.
>
> This restricts what you can do with strings, since most the 
> std.string functions allocate new strings for their return 
> values...

Is there a way to do thread-local allocations?