Avoid copying ManyToMany table results#5923
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danpat merged 1 commit intoProject-OSRM:masterfrom Jan 4, 2021
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Regardless of any copy elision on the returned pair value, the duration and distance results are always copied. Fix this by passing rvalue references to std::make_pair.
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The big benefit here is probably going to be reduce memory footprint under heavy load when making lots of concurrent matrix requests - I suspect the overall performance improvement will be really small. The copy only happens once per request, not within the compute intensive routing loop. Definitely a good change though, 👍 I think the CI failure is good to ignore - it's a coverage check, which seem to be a bit noisy when only a couple of lines change. |
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@jcoupey sorry I don't have any numbers. I just noticed it and thought it would be a quick win. |
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Issue
Regardless of any copy elision on the returned pair value, the duration and distance results are always copied.
Fix this by passing rvalue references to
std::make_pair.This could save copying a few megabytes on
TableandTriprequests with hundreds of sources/destinations and waypoints respectively. I haven't profiled this to see if this affects performance in any other way.Tasklist