On 11/7/14 1:05 AM, H. S. Teoh via Digitalmars-d wrote:
A little more investigation revealed the culprit: a queue object implemented with subarrays, and subarrays were being used as stacks by appending with ~= and popping by decrementing .length. A dangerous combination that causes excessive reallocations! After inserting assumeSafeAppend() in the right place, the memory consumption rate dropped to more reasonable levels. It's still visibly faster than when GC is enabled, so probably there are other places with excessive allocations, but this particular change stood out because after adding assumeSafeAppend() to the code, the solver's performance *even with GC enabled* improved by about 40%-50%. So this explains why calling GC.disable() had such a pronounced effect before: the GC is too busy cleaning up after unnecessarily allocation-hungry code!
In D1 this would have worked fine. A "queue array" wrapper may be a good candidate for Phobos that works just like a normal array but calls assume safe append whenever decrementing length.
-Steve
