On Monday, 8 September 2014 at 17:06:34 UTC, badlink wrote:
Hello,
I'm creating a real-time 3D app using std.concurrency for
exchanging messages between the renderer and a few mesher
threads.
The app runs fine, but once in a while I get a consistent FPS
drop.
Already aware that the cause is the GC (a call to GC.disable
eliminates the slowdowns) I timed all functions and found that
spawn() sometimes requires more than 50 ms to returns.
I did a quick search through Phobos and found out that the
Mailbox implementation in std.concurency uses a private List
struct where every call to .put() needs to allocate a new node
:(
Why is that ?
I would have used for example a ring buffer which can do all
the things the Mailbox needs and faster in every way. The
growing time can be compensated by a right call to
setMaxMailboxSize() and any random removal can be a swap of the
last element with the one being removed.
AFAICS, the documentation doesn't write about any ordering
guarantees of messages, but I can imagine that there are implicit
expectations. In particular prioritySend() could break, if the
implementation isn't done carefully.
