As I said above this does not happen with either cypari or cypari2 when
using getno.
This is not a cypari issue. The issue is that Sage creates a "unique"
object for each new number field, where new means that the input parameters
for the NumberField function have not been used before. The number field
objects are stored in a cache indexed by a key generated from the input
parameters. Those cached objects live for the entire session. This is by
design. The design did not anticipate creating a billion number fields in
one Sage session. That was not necessarily a bad choice.
Perhaps there is a way of disabling caching or clearing the cache.
- Marc
On Sun, Sep 8, 2024, 1:02 PM Dima Pasechnik <dimp...@gmail.com> wrote:
> Can this be reproduced in plain Python with cypari2 installed?
> One would need to replace the call to NumberField with the corresponding
> cypari2 equivalent.
> This would at least tell whether it's a leak in cypari2, or not.
>
> Dima
>
>
>
>
>
> On 8 September 2024 17:03:54 BST, 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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