For me this code is rather unpredictable, as ipython and prompt_toolkit kick in
and produce extra objects.
For consistency (at least them the output values are reproducible)
it looks better to experiment with Sage's python (./sage --python)
for which the code needs to be adjusted, with "^" replaced by "**", and
two lines added as the front:
from sage.all import *
var('x')
On Sun, Sep 8, 2024 at 5:03 PM Nils Bruin <nbr...@sfu.ca> wrote:
>
> This example is definitely leaving loads of stuff on the python heap, so if
> there is a leak onto the cython heap then it is not the only one. My guess
> would be an interaction with the coercion system or UniqueRepresentation,
> which both keeps global weak references to objects. If the key information
> ends up containing objects that hold a reference to the values in a weakly
> valued dictionary, the garbage collector can not remove the cycle. These
> things are hellish to debug. The code below does find the relevant objects on
> the heap, though, so you can plot the backwards reference graphs of some of
> these objects to see what kinds of links are involved. We have resolved some
> of these bugs in the past.
>
> ```
> import gc
> from collections import Counter
>
> gc.collect()
> pre={id(a) for a in gc.get_objects()}
>
> for A2 in range(1, 1000):
> Kn=NumberField(x^2+A2,'w')
> m=Kn.class_group().order()
> del Kn, m
>
> gc.collect()
> gc.collect()
> T=Counter(str(type(a)) for a in gc.get_objects() if id(a) not in pre)
> T
> ```
> Notes for the code above:
> - if you run it twice you get a nearly empty list from T, which is
> consistent with UniqueRepresentation objects remaining (they would not be
> recreated if they already exist).
> - this is confirmed by rerunning the loop but now with another name than 'w'
> for Kn. Now new objects do get created!
>
> On Wednesday 4 September 2024 at 06:09:37 UTC-7 Georgi Guninski wrote:
>>
>> Probably this shares the same bug as [1]
>>
>> Calling `NumberField().class_group().order()` in a loop of size N:
>> #10^3 leaks: 40.03 MB 40026112 pari= [7950, 1451665]
>> #10^4 leaks: 338.49 MB 338493440 pari= [83505, 19297360]
>>
>> The leak appears to be in the pari heap.
>>
>> Code .sage:
>> ====
>> #Author Georgi Guninski Wed Sep 4 12:58:18 PM UTC 2024
>> #10^3 leaks: 40.03 MB 40026112 pari= [7950, 1451665]
>> #10^4 leaks: 338.49 MB 338493440 pari= [83505, 19297360]
>>
>> import psutil,gc,sys
>>
>> from sage.all import EllipticCurve
>> ps = psutil.Process()
>> num=10**3 #10**5 // 2
>> x=var('x')
>> def leaknf5(N=10**3):
>> gc.collect()
>> base = ps.memory_info().rss
>> for A2 in range(1, N):
>> Kn=NumberField(x^2+A2,'w')
>> m=Kn.class_group().order()
>> gc.collect()
>> mem = ps.memory_info().rss - base
>> print(f"{mem/1e6 :.2f} MB ",mem," pari=",pari.getheap())
>>
>> leaknf5(10**4)
>> ====
>>
>> [1]: https://groups.google.com/g/sage-devel/c/fWBls6YbXmw
>> Memory leak in |EllipticCurve([n,0]).root_number()| and problem in
>> algebraic geometry
>
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