RFR: 8260555: Change the default TIMEOUT_FACTOR from 4 to 1 [v4]

[Magnus Ihse Bursie]

On Wed, 20 Aug 2025 15:21:39 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> Leo Korinth has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   after suggestion from Daniel
>
> It seems to me like there is a need to automatically collect normal test run times automatically, so we can match the timeout given to any individual test with the normal execution time. After all, the purpose of any timeout on tests is to allow the test to execute normally, but not wait too long in case of a problem that causes the test to take too long (or forever) to run.
> 
> I realize that this is highly hardware dependent, but test times tend to be Pareto distributed, so a very quick test maybe takes 1 second on fast machines and 10 on slow, and very slow tests maybe take 15 minutes on fast machines and 40 minutes on slow. In the first case, anything above 15 seconds is probably sus, and in the second case, anything above 60 is probably not good either (I'm just adding 50% to the max time). 
> 
> Right now it seems engineers is spending their valuable time giving guesstimates for each individual test. That seems like poorly used time and resources.

> @magicus unfortunately that is often not the case in practice. We can see many tests that normally run very quickly but occasionally run very slow - minutes versus seconds.

That is surprising and a bit disappointing. I guess it is not worth the effort to try and figure out why this is the case; it could probably vary from test to test and be difficult to track for little gain. Still, it makes you wonder.

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PR Comment: https://git.openjdk.org/jdk/pull/26749#issuecomment-3210365303