RuntimeError: instance.__dict__ not accessible in restricted mode

[Max Bowsher <maxb1@…>]

In all probability, this is not a bug in Trac, but in either Subversion, SWIG, or mod_python - I am filing this ticket principally so that there is somewhere to collect reports of this problem, and make notes of any debugging that is done.

I experience an intermittent Trac internal error, with the following environment:

• Debian 'etch'
• SWIG 1.3.28-1.1
• Apache HTTPD 2.2.2
• Subversion 1.3.2 (using the above SWIG)
• mod_python 3.2.9-rc3
• Trac 0.10dev r3492

Traceback (most recent call last):
  File "/home/maxb/wc/trac/trunk/trac/web/main.py", line 314, in dispatch_request
    dispatcher.dispatch(req)
  File "/home/maxb/wc/trac/trunk/trac/web/main.py", line 199, in dispatch
    resp = chosen_handler.process_request(req)
  File "/home/maxb/wc/trac/trunk/trac/versioncontrol/web_ui/browser.py", line 95, in process_request
    repos = self.env.get_repository(req.authname)
  File "/home/maxb/wc/trac/trunk/trac/env.py", line 194, in get_repository
    return RepositoryManager(self).get_repository(authname)
  File "/home/maxb/wc/trac/trunk/trac/versioncontrol/api.py", line 70, in get_repository
    self.repository_dir, authname)
  File "/home/maxb/wc/trac/trunk/trac/versioncontrol/svn_fs.py", line 262, in get_repository
    repos = SubversionRepository(dir, authz, self.log)
  File "/home/maxb/wc/trac/trunk/trac/versioncontrol/svn_fs.py", line 279, in __init__
    self.pool = Pool()
  File "/home/maxb/wc/trac/trunk/trac/versioncontrol/svn_fs.py", line 158, in __init__
    self._pool = core.svn_pool_create(self._parent_pool())
  File "/usr/local/lib/svn-python/svn/core.py", line 177, in svn_pool_create
    return Pool(parent_pool)
  File "/usr/local/lib/svn-python/libsvn/core.py", line 1050, in svn_pool_create
    return apply(_core.svn_pool_create, args)
  File "/usr/local/lib/svn-python/libsvn/core.py", line 2868, in _wrap
    obj.set_parent_pool(self)
  File "/usr/local/lib/svn-python/libsvn/core.py", line 2781, in set_parent_pool
    self._parent_pool = parent_pool or application_pool
  File "/usr/local/lib/svn-python/libsvn/core.py", line 2766, in <lambda>
    __setattr__ = lambda self, name, value: _swig_setattr(self, apr_pool_t, name, value)
  File "/usr/local/lib/svn-python/libsvn/core.py", line 22, in _swig_setattr
    return _swig_setattr_nondynamic(self,class_type,name,value,0)
  File "/usr/local/lib/svn-python/libsvn/core.py", line 17, in _swig_setattr_nondynamic
    self.__dict__[name] = value
RuntimeError: instance.__dict__ not accessible in restricted mode

Some googling suggests that this error is a hint that a Python object created in one subinterpreter is being used in a different subinterpreter. This is supported by the fact that my Trac setup does indeed involve Trac instances running under multiple subinterpreters.