On Wednesday, March 23, 2016 at 9:17:58 AM UTC-7, vdelecroix wrote:
>
> Hello,
>
> Some friend just sent an e-mail to me mentioning a memory leak. Here is
> a minimal example
>
> sage: x = polygen(ZZ)
> sage: K = NumberField(x**3 - 2, 'cbrt2', embedding=RR(1.2599))
> sage: w = K.gen()
> sage: import resource
> sage: resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
> 180720
> sage: for _ in range(10000): test = w > 1
> sage: resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
>
I tried python-level analysis:
import gc
from collections import Counter
gc.collect()
pre={id(c) for c in gc.get_objects()}
x = polygen(ZZ)
K = NumberField(x**3 - 2, 'cbrt2', embedding=RR(1.2599))
w = K.gen()
gc.collect()
pre={id(c) for c in gc.get_objects()}
for _ in range(20000): test = w > 1
gc.collect()
gc.collect()
post=Counter(type(o) for o in gc.get_objects() if id(o) not in pre)
sorted(post.iteritems(),key=lambda t: t[1])
C=[c for c in gc.get_objects() if id(c) not in pre and type(c) is tuple and
type(c[0]) is sage.rings.real_mpfi.RealIntervalFieldElement]
This finds a whole bunch of one-element tuples with a realintervalfield
element. If I use objgraph_showbackrefs(C[100]) or something similar, I
only get the references via C! So it seems somehow these objects survived
"gc.collect" without actually having objects referring to them. That would
point towards an incref/decref error somewhere.
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