Recent test-suite slowdown

[dmnks]

Running the test-suite on an old(er) branch (e.g. rpm-4.19.x) takes about 45s on my laptop. The current master (before #3535) shows 2:57s here. The number of tests is similar in both cases (about 560) so it must be something else. Should be relatively easy to bisect one of these (Fri)days.

[dmnks]

Turns out, this is most likely just the address sanitizer stuff 😅 I only started configuring my builds with that enabled (ENABLE_ASAN and ENABLE_UBSAN) only recently. Thanks @pmatilai for suggesting this to be the culprit.

Running the suite without those two build flags yields ~1:13s on my machine, which sounds about right (given the amount of added tests over the years).

[dmnks]

I guess that closes the case here. Lesson learned - ASAN/UBSAN add "a bit" of overhead (it's always a tradeoff), surprise surprise. If one's impatient with the test execution time, keep a non-ASAN/UBSAN build on the side and run the suite there 😄 (CI still runs with it enabled, don't worry).

[pmatilai]

Yeah, while usually ASAN is well worth it, when working on test-suite rather than the code, the ability to cut execution time in half is a very useful thing 😅

[dmnks]

Yep, the difference is quite astonishing for sure. I was never aware of how much overhead it adds until actually enabling it for my builds 😅

I'll add a short note to tests/README.md about this, I guess 😄