On 7/25/2013 11:30 AM, Adam D. Ruppe wrote:
The biggest compile time killer in my experience is actually running out of
memory and hitting the swap.
My work app used to compile in about 8 seconds (on Linux btw). Then we added
more and more stuff and it went up to about 20 seconds. It uses a fair amount of
CTFE and template stuff, looping over almost every function in the program to
generate code.
Annoying... but then we added a little bit more and it skyrocketed to about 90
seconds to compile! That's unbearable.
The cause was the build machine had run out of physical memory at the peak of
the compile process, and started furiously swapping to disk.
I "fixed" it by convincing them to buy more RAM, and now we're back to ~15
second compiles, but at some point the compiler will have to address this. I
know donc has a dmd fork where he's doing a lot of work, completely
re-engineering CTFE, so it is coming, but that will probably be the next speed
increase, and we could be looking at as much as 5x in cases like mine!
I know the memory consumption is a problem, but it's much harder to fix.
BTW apparently a dmd built with Microsoft's compile does the nasty in about 11
seconds rather than 30 for the std.algorithm build - comparable to the linux
version with gcc. I really like dmc too, but a 3x speed increase is really
significant for something that's relatively easy to do.
An interesting project would be to research the specific cause of the
difference.
