[Python-Dev] Making "-j0" the default setting for the test suite?

[Terry Reedy]

On 1/28/2018 11:43 PM, Guido van Rossum wrote:
> So why can't you just run "make test" if that's faster?

Not a standard option on Windows ;-).

> On Sun, Jan 28, 2018 at 8:30 PM, Nick Coghlan <ncoghlan at gmail.com 
> <mailto:ncoghlan at gmail.com>> wrote:
> 
>     On my current system, "make test" runs in around 3 minutes, while
>     "./python -m test" runs in around 16 minutes. And that's with "make
>     test" actually running more tests (since it enables several of the
>     "-u" options).
> 
>     The difference is that "make test" passes "-j0" and hence not only
>     uses all the available cores in the machines, but will also run other
>     tests while some tests are sleeping.
> 
>     How would folks feel about making "-j 0" the default in the test
>     suite, and then adjusted the handling of "-j 1" to switch back to the
>     current default single process mode?
> 
>     My rationale for that is to improve the default edit-test cycle in
>     local development, while still providing a way to force single-process
>     execution for failure investigation purposes.

I would like this (though I could write a .bat file).  I routinely pass 
-j14 or so on a 6 core x 2 processes/core machine and get about the same 
times.  The speedup would be even better but for the last very long 
running test.  I wish each test file was limited to about 30 seconds, or 
even a minute.

-- 
Terry Jan Reedy