Demo issue #86

[arnaud-lb]

The purpose of this PR is to demonstrate issue sebastianbergmann/phpunit#4918 (I'm not requesting this to be merged).

HangingDemoTest executes Differ::diff() on two large strings. Differ::diff() hangs for hours in this case.

(The test skips itself if the CI environment variable is set, so that it doesn't consume github action quota.)

[sebastianbergmann]

Thank you for your contribution. I appreciate the time you invested in preparing this pull request. However, I have decided not to merge it.

[SpacePossum]

Thanks for building the demo 👍
Do you get different result when using MemoryEfficientLongestCommonSubsequenceCalculator or TimeEfficientLongestCommonSubsequenceCalculator when calling diff?
I wonder if this an issue within both calculators or if something in selectLcsImplementation can be tweaked.

[arnaud-lb]

Yes, I'm getting different results depending on the calculator being used. MemoryEfficientLongestCommonSubsequenceCalculator is the one being used by default in this case (it's the one being choosen by selectLcsImplementation). I've tried with TimeEfficientLongestCommonSubsequenceCalculator, and it uses at least 4GB of memory (I haven't tried with a higher memory limit).

[SpacePossum]

OK, yeah than the only solution I see would to be to develop another calculator for this use case. It is not something I can pick up any time soon, hope someone else might step forward.