I had an error like this and it turned out to be caused by a GC error. Specifically, an object A was allocated, then erroneously deallocated (but there was still stuff pointing to it). Object B was then allocated, with memory overlapping that of object A. Object A was then modified, and that modified the refcount field of object B. That might be a variant of what's going on here.
I tracked it down by using gdb's watch command on the object with the weird ref count... - Robert On Oct 30, 2007, at 12:19 AM, mabshoff wrote: >>> As I wrote above: The issues with the refcount going insane is a >>> nice >>> result from the debugging and that will hopefully lead to some >>> improvements in our fight against memleaks. >> >> Thanks and good luck, > > Carl had some interesting input: > > [02:03] <cwitty> I was looking at those refcounts some more. > [02:03] <mabshoff> ok > [02:03] <cwitty> It turns out that Python caches and shares small int > objects: > [02:04] <cwitty> sage: a = int(0) > [02:04] <cwitty> sage: sys.getrefcount(a) > [02:04] <cwitty> 6288 > [02:04] <cwitty> sage: b = int(0) > [02:04] <cwitty> sage: sys.getrefcount(a) > [02:04] <cwitty> 6289 > [02:04] <cwitty> sage: a is b > [02:04] <cwitty> True > [02:04] <mabshoff> ok > [02:04] <cwitty> So the reference-counting problem could be anywhere > that deals with small Python ints. > [02:05] <mabshoff> mmmh. > [02:05] <mabshoff> So it is not the list [0], but the smallint 0 that > has the reference counter overflow? > [02:06] <cwitty> Let me go look at your printouts again. I thought > so, but I didn't look closely. > [02:06] <cwitty> Yeah, that's what it looks like to me. (Just judging > from your next-to-latest e-mail.) > [02:07] <mabshoff> Because the numbers "jump", while I would expect > them to increase by 1 each time. > [02:11] <cwitty> So it looks like between your first and second > printouts, the refcount for "0" jumped by 135, and the refcount for > "1" jumped by at least 125 (to make it wrap). > [02:11] <mabshoff> Yep, otherwise it would take *forever* to even wrap > on a 32 bit box. > > So now comes the question: Why doesn't the refcount get decremented? > How do we fix this? > >> >> Jaap > > Cheers, > > Michael > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://sage.scipy.org/sage/ and http://modular.math.washington.edu/sage/ -~----------~----~----~----~------~----~------~--~---
