[Python-Dev] A little GC confusion (original) (raw)

Kevin Jacobs jacobs@penguin.theopalgroup.com
Thu, 21 Feb 2002 08:38:42 -0500 (EST)

On Thu, 21 Feb 2002, David Abrahams wrote:

The following extension module (AA) is a reduced example of what I'm doing to make extension classes in 2.2. I followed the examples given by typeobject.c. When I "import AA,pdb" I get a crash in GC. Investigating further, I see this makes sense: GC is enabled in classmetatypeobject, yet classtypeobject does not follow the first rule of objects whose type has GC enabled:

"The memory for the object must be allocated using PyObjectGCNew() or PyObjectGCVarNew()." So, I guess the question is, how does PyBaseObjectType (also statically allocated) get away with it?

I doesn't have any time to really look at your code, but I thought I'd point out a trick that several extension modules use to protect statically allocated type objects. Here is the code from socketmodule.c:

/* static PyTypeObject PySocketSock_Type = { . . . 0, /* set below / / tp_alloc / PySocketSock_new, / tp_new / 0, / set below / / tp_free */ };

/* buried in init_socket */ PySocketSock_Type.tp_alloc = PyType_GenericAlloc; PySocketSock_Type.tp_free = _PyObject_Del;

This trick ensures that the static type object is never freed.

Also, there is a funny-looking line in your PyTypeObject:

0, [file://&PyBaseObject_Type,](https://mdsite.deno.dev/file://&pybaseobject%5Ftype,/)                     /* tp_base */

-Kevin

-- Kevin Jacobs The OPAL Group - Enterprise Systems Architect Voice: (216) 986-0710 x 19 E-mail: jacobs@theopalgroup.com Fax: (216) 986-0714 WWW: http://www.theopalgroup.com