Fix process of reference count during GC

[y-fujisaki2]

When we subtract reference counter of an object, the destructor is automatically called if the value of counter is 0.
At the same time an error occurs, as the GC executed while the destructor is still in running phase.
To eliminate the error, we have added below program which exclude objects from GC in the destructor in line 4.

static void
Wrapper_dealloc(Wrapper *self)
{
PyObject_GC_UnTrack((PyObject )self); //Add this line to eliminate self from GC
Wrapper_clear(self);
self->ob_type->tp_free((PyObject)self);
}

Patch: ZODB3-3.10.7.zip

[y-fujisaki2]

Thanks so much for marging this fix.

[jamadden]

@y-fujisaki2 I am curious: you have posted bug reports about this issue to many repositories that I follow. I saw the original Python big report. What made you file all of these other big reports, like this one here, especially against such old versions? Have you experienced any crashes?

[y-fujisaki2]

Thank you for your follows. Using Python 2.7, we got a core file. So we investigated to confirm whether there weren't other problems which are the same state at all zope and python sources.