Thats the expected behavoir. Without type annotation, cython just does the same as Python (create a list of 10**8 elements and iterate over). With type annotation it is a C-level for loop.
On Thursday, October 20, 2016 at 12:33:47 AM UTC+2, Sébastien Labbé wrote: > > Dear sage-devel, > > Writing cython code, I was having a problem with memory leaks, and I > managed to simplify the problem to a simple for loop computing a sum. > > If the loop variable a is cdef, everything is fine: > > sage: %%cython > ....: def test_with_cdef_a(int N): > ....: cdef long S = 0 > ....: cdef int a > ....: for a in range(1, N): > ....: sig_check() # Check for Keyboard interupt > ....: S += a > ....: return S > ....: > sage: %time test_with_cdef_a(10**8) # fast, takes no memory, great > CPU times: user 103 ms, sys: 2.64 ms, total: 105 ms > Wall time: 106 ms > 4999999950000000 > > As expected, if I forget the "cdef int a" line, it takes longer. But most > surprisingly, it uses a *lot* of memory during the computation (40%) and > not all of the memory is freed after he computation (30%). > > sage: %%cython > ....: def test_no_cdef_a(int N): > ....: cdef long S = 0 > ....: for a in range(1, N): > ....: sig_check() # Check for Keyboard interupt > ....: S += a > ....: return S > ....: > sage: %time test_no_cdef_a(10**8) # this takes a lot of memory > (40%) + memory leaks (30% of the memory after computation) > CPU times: user 8.36 s, sys: 787 ms, total: 9.14 s > Wall time: 9.24 s > 4999999950000000 > sage: %time test_no_cdef_a(10**9) # this takes a lot of memory (all > of it, starts swaping) > > I am using: > > $ sage -cython -V > Cython version 0.24.1 > $ sage -version > SageMath version 7.4.beta6, Release Date: 2016-09-24 > > Are you able to reproduce? > > Sébastien > > > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
