On Thursday, 18 February 2016 at 13:00:12 UTC, Witek wrote:
So, the question is, why is D / DMD allocator so slow under
heavy multithreading? The working set is pretty small (few
megabytes at most), so I do not think this is an issue with GC
scanning itself. Can I plug-in tcmalloc / jemalloc, to be used
as the underlying allocator, instead of using glibc? Or is D
runtime using mmap/srbk/etc directly?
Thanks.
Currently, all memory allocations use a global GC lock[1]. As
such, presently high-parallelism programs need to avoid
allocating memory via the GC.
You can avoid this problem by using a different allocation /
memory management strategy. You may want to have a look at
std.experimental.allocator.
[1]:
https://github.com/D-Programming-Language/druntime/blob/30f8c1af39eb17d8ebec1f5fd401eb5cfd6b36da/src/gc/gc.d#L348-L370
