On Thursday, 2 October 2014 at 20:16:56 UTC, Gary Willoughby
wrote:
Say i have created a program written in D, what tools are
available for me to track memory allocations?
If you write a program and its performance is slow because you
suspect too many allocations are taking place in unrecognised
areas, what tools or techniques do you use to find where they
are and eliminate them?
If *time* spent by allocations is a problem, profile with `perf
top` (assuming you have Linux): Look for 'gc', 'malloc',
'calloc', etc.
(Plain perf record will also work, but not be as
quick/interactive. CodeXL works too.)
See https://perf.wiki.kernel.org/index.php/Tutorial - you
probably need some specific arguments to get caller info, didn't
use it for a while so I don't remember.
If e.g. the GC is an issue, it should be immediately evident with
some GC function taking e.g. over 5% of time. Usually the actual
overhead will be much higher but divided into multiple smaller
functions that will take little time individually. Drill down
into one of these and look at its callers. Eliminate the most
common source of calls, look again, repeat. Usually removing a
source of alloc calls will result in better speedup than the
profiler suggests.
If *space* is a problem, Valgrind doesn't work with most D
programs for some reason (probably D's fault), so, good luck with
that. But eliminating the biggest time wasters usually helps
space as well (or rather, it makes it more controllable as you
know better where you allocate memory).