2010/6/1 <sm...@gmx.net>: >> This said, there may be a bug somewhere, but what do you want us to look >> at? >> Do you have a case that we could reproduce and investigate? >> >> -- >> Amaury Forgeot d'Arc > > Thank you, I'm not a C-Developer, > but still I have one more detail: > > I call py_decRef( pyObj) of dll (version 3.1.1), > ( which calls tp_dealloc, which calls my freeMem() method)) > No problem is reported here. > Now, the freed memory should not be accessed anymore by python31.dll. > You may fill the freed pyObjectHead with invalid values, > in my case it's: ob_refcnt= 7851148, ob_type = $80808080 > > But later, when I call Py_Finalize, > there inside is some access to the same freed memory; > this causes an AV, more precisely, > when the value $80808080 is checked. > > My Delphi-Debugger shows the following byte-sequence inside python31.dll: > 5EC3568B7424088B4604F74054004000007504 > > 5E - pop esi > C3 - ret > 56 - push esi > 8B742408 - mov esi, [esp+$08] > 8B4604 - mov eax, [esi+$04] > // eax = $80808080 // > > F7405400400000 - test [eax+$54], $00004000 > // AV exception by read of address $808080D4 // > > 7504 - jnz $1e03681b > > > Maybe this can help someone, thank you!
I'm sorry but this kind of issue is difficult to investigate without the source code. Normally I would compile everything (python & your program) in debug mode, and try to see why the object is used after tp_dealloc. For example, it's possible that your code does not handle reference counts correctly A call to Py_INCREF() may be missing somewhere, for example. This is a common error. tp_dealloc() is called when the reference count falls to zero, but if the object is still referenced elsewhere, memory will be accessed again! Without further information, I cannot consider this as a problem in Python. I know other extension modules that manage memory in their own way, and work. It's more probably an issue in the code of your type. -- Amaury Forgeot d'Arc _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
