scrape_test.go: Increase scrape interval in TestScrapeLoopCache to re…

[machine424]

…duce potential flakiness

fixes: #12727

[bboreham]

Thanks; needs DCO.

Will this increase the test run time?

[machine424]

Will this increase the test run time?

Yep, it'll move from 0.04s to 0.4s in average.
Another solution would be to add a time.Sleep(2*time.Millisecond) to the scraper.scrapeFunc to make sure it isn't triggered at the same ms timestamp.

[bboreham]

How about we make this change only on the OSs where it is required? (Which I think is Windows)

[machine424]

How about we make this change only on the OSs where it is required? (Which I think is Windows)

I have the same issue on Mac actually.

I could exclude both of them if you want, and maybe wait for the test to fail on linux one day :)

[machine424]

There is also this hack:

Another solution would be to add a time.Sleep(2*time.Millisecond) to the scraper.scrapeFunc to make sure it isn't triggered at the same ms timestamp.

Which will not increase the runtime A LOT (given golang/go#44343)

(fun fact: we don't recommend using such small scrape intervals, but they're the ones we "test" the most so tests run faster, I don't know if parallelism may help to be able ti use larger intervals...)

[bboreham]

OK let's move ahead with this and revisit if the extra fraction of a second is important.