Hi 👋 How did you find this issue?

Hi 👋 How did you find this issue?

Hi!
I was looking for similar improvements, as in !11332, and noticed how much the removal of a single array_map improved performance. Inspired by that, I started exploring other areas and realized that the size function could be optimized to use only one iteration of identityMap instead of two.
This refactor is not linked to any specific issue at the moment.

Ok. I was wondering because I was not able to find any call to that method in the project. Better performance comes at a legibility cost. For !11332, that cost was more than justified, but here, I don't think it is, by your own admission. Maybe a better approach would be to start by hunting for array_map in a real world trace?

The only reference I was able to find is in this docs->working-with-objects.rst. Despite the fact that this refactor remove an iteration and could be useful if other projects use this size function I agree with you.
I'll hunt for other improvements and try to get a benchmark/trace of it.

ps: there is any documentation of how to trace improvements and time of execution in doctrine for contribution?

I don't know if there is any docs on this, however I do know that we have phpbench benchmarks here: https://github.com/doctrine/orm/tree/3.3.x/tests/Performance

If I had to hunt for improvements, I think I would use xdebug, blackfire or datadog features and would hunt for calls to array_map in traces. With xdebug, you can get a full trace with xdebug_start_trace()