python object is not garbage collected when it's in a javascript closure

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What steps will reproduce the problem?

Run the following code (also attached):

import gc
import sys
import inspect
import weakref

import PyV8


class PyObj(object):
    def __init__(self):
        pass

class Global(object):
    def Obj(self):
        return PyObj()

    def out(self, v):
        print "-- Script out: %s --" % (v,)


tracks = []
def obj_gone(ref):
    print "**Obj deleted**"
def track_obj(obj):
    tracks.append(weakref.ref(obj, obj_gone))


def run_case(name, js):
    print "Case %s:" % (name,)
    ctxt = PyV8.JSContext(Global())
    with ctxt:
        obj = ctxt.eval(js)
        track_obj(obj)

        print "refcount:", sys.getrefcount(obj)
        print "V8 theObj=null"
        ctxt.eval("theObj = null;")
        print "Py obj=None"
        obj = None
        print "V8 gc"
        PyV8.JSEngine.collect()
        print "Py gc"
        gc.collect()
        print "Py gc.garbage:", gc.garbage
    print


gc.set_debug(gc.DEBUG_COLLECTABLE | gc.DEBUG_UNCOLLECTABLE |
             gc.DEBUG_INSTANCES | gc.DEBUG_OBJECTS)

run_case("one", """
    function tighty() {
        var localObj = Obj();
        localObj.foobar = function () {
            out("hi" + this);
        };
        return localObj;
    }
    var theObj = tighty();
    theObj.foobar();
    theObj;""")

run_case("two", """
    function tighty() {
        var localObj = Obj();
        localObj.foobar = function () {
            out("hi" + localObj);
        };
        return localObj;
    }
    var theObj = tighty();
    theObj.foobar();
    theObj;""")


What is the expected output? What do you see instead?

I expect the object to get deleted in both cases, that is:

-- Script out: hi[object Object] --
refcount: 3
V8 theObj=null
Py obj=None
V8 gc
**Obj deleted**
Py gc
Py gc.garbage: []

However, in the second case, the object is never deleted:

Case two:
-- Script out: hi[object Object] --
refcount: 3
V8 theObj=null
Py obj=None
V8 gc
Py gc
Py gc.garbage: []

What version of the product are you using? On what operating system?

Python 2.6.6 with PyV8-1.0-preview-r443.win32-py2.6.exe on Windows 7

Please provide any additional information below.

Seems to be an issue with how V8's garbage collector interacts w/ Python 
objects within closures... it seems to not release its reference counts even 
though it's no longer accessible from anywhere. 

Original issue reported on code.google.com by [email protected] on 17 Jul 2013 at 7:29

Attachments:

• pyv8-bug-186.py