Here's the result of "./python -m test test_decimal -m test_maxcontext_exact_arith":

0:00:00 load avg: 1.33 Run tests sequentially
0:00:00 load avg: 1.33 [1/1] test_decimal
python(7835,0x11a218dc0) malloc: can't allocate region
:*** mach_vm_map(size=842105263157895168, flags: 100) failed (error code=3)
python(7835,0x11a218dc0) malloc: *** set a breakpoint in malloc_error_break to debug
python(7835,0x11a218dc0) malloc: can't allocate region
:*** mach_vm_map(size=842105263157895168, flags: 100) failed (error code=3)
python(7835,0x11a218dc0) malloc: *** set a breakpoint in malloc_error_break to debug
python(7835,0x11a218dc0) malloc: can't allocate region
:*** mach_vm_map(size=421052631578947584, flags: 100) failed (error code=3)
python(7835,0x11a218dc0) malloc: *** set a breakpoint in malloc_error_break to debug
python(7835,0x11a218dc0) malloc: can't allocate region
:*** mach_vm_map(size=421052631578947584, flags: 100) failed (error code=3)
python(7835,0x11a218dc0) malloc: *** set a breakpoint in malloc_error_break to debug

== Tests result: SUCCESS ==

1 test OK.

Total duration: 553 ms
Tests result: SUCCESS




I spent quite a time to find where this error was coming from and it's actually not an error but a dubious message from OSX. Others will surely lose time on this too, I think the best way to handle it is to use bigmemtest() with a small value on MacOS so that it's only run when '-M' is given on this platform, but always on the others.