This past June problems were reported with seeing messages like the
following on stderr when running pylint:
Exception RuntimeError: 'maximum recursion depth exceeded while
calling a Python object' in <type 'exceptions.AttributeError'>
ignored
At the time it was attributed to a bug in Python 2.6.2. However, after
upgrading to Python 2.6.4 I still saw the problem, so decided to
investigate further, and eventually tracked it down to an infinite
recursion in logilab-astng
I have attached a Python file which triggers the problem. The call
stack which produces the message is as follows:
0 File "C:\Python26\Scripts\pylint.bat", line 12, in <module>
lint.Run(sys.argv[1:])
1 File
"C:\Python26\lib\site-packages\pylint-0.18.1-py2.6.egg\pylint\lint.py",
line 884, in __init__
linter.check(args)
2 File
"C:\Python26\lib\site-packages\pylint-0.18.1-py2.6.egg\pylint\lint.py",
line 501, in check
self.check_astng_module(astng, checkers)
3 File
"C:\Python26\lib\site-packages\pylint-0.18.1-py2.6.egg\pylint\lint.py",
line 578, in check_astng_module
if implements(checker, IASTNGChecker)])
4 File
"C:\Python26\lib\site-packages\pylint-0.18.1-py2.6.egg\pylint\lint.py",
line 595, in astng_events
self.astng_events(child, checkers, _reversed_checkers)
5 File
"C:\Python26\lib\site-packages\pylint-0.18.1-py2.6.egg\pylint\lint.py",
line 595, in astng_events
self.astng_events(child, checkers, _reversed_checkers)
6 File
"C:\Python26\lib\site-packages\pylint-0.18.1-py2.6.egg\pylint\lint.py",
line 592, in astng_events
checker.visit(astng)
7 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\utils.py",
line 320, in visit
method(node)
8 File
"C:\Python26\lib\site-packages\pylint-0.18.1-py2.6.egg\pylint\checkers\typecheck.py",
line 207, in visit_callfunc
called = safe_infer(node.func)
9 File
"C:\Python26\lib\site-packages\pylint-0.18.1-py2.6.egg\pylint\checkers\utils.py",
line 38, in safe_infer
value = inferit.next()
10 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\infutils.py",
line 203, in wrapped
for res in _func(node, context, **kwargs):
11 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\infutils.py",
line 231, in wrapper
for node in func(*args, **kwargs):
12 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\inference.py",
line 281, in infer_getattr
for obj in owner.igetattr(self.attrname, context):
13 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\infutils.py",
line 265, in igetattr
self._wrap_attr(self.getattr(name, context, lookupclass=False),
context),
14 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\infutils.py",
line 248, in getattr
return self._proxied.instance_attr(name, context)
15 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\inference.py",
line 53, in _set_proxied
if not hasattr(const, '__proxied'):
16 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\infutils.py",
line 44, in __getattr__
return getattr(self._proxied, name)
17 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\inference.py",
line 53, in _set_proxied
if not hasattr(const, '__proxied'):
18 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\infutils.py",
line 44, in __getattr__
return getattr(self._proxied, name)
19 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\inference.py",
line 53, in _set_proxied
if not hasattr(const, '__proxied'):
20 File
"C:\Python26\lib\site-packages\logilab_astng-0.19.1-py2.6.egg\logilab\astng\infutils.py",
line 44, in __getattr__
return getattr(self._proxied, name)
and so on...
What is happening is that Instance.getattr (entry 14 in the call stack)
is accessing the _proxied attribute of the node. This attribute is
actually a property whose getter is the _set_proxied function (entry 15
in the call stack). The first thing this function does is call hasattr
on the node to see if it has a __proxied attribute. Because this
attribute does not yet exist on the node, the node's __getattr__ method
is invoked (entry 16 in the call stack). It in turn attempts to call
getattr on its _proxied attribute. This in turn invokes the _proxied
property's _set_proxied function (entry 17 in the call stack), resulting
in infinite recursion.
To reproduce, run
pylint -r n -f parseable bug.py
on the attached bug.py. I've also attached my .pylintrc.
Here's the output from running pylint --version on my system:
pylint.bat 0.18.1,
astng 0.19.1, common 0.45.2
Python 2.6.4 (r264:75708, Oct 26 2009, 08:23:19) [MSC v.1500 32 bit (Intel)]
I don't understand what the inference system is doing well enough to
know how to fix the problem, but hopefully this will give someone enough
information to work on it.
Daniel Harding
'a'.strip()
# lint Python modules using external checkers.
#
# This is the main checker controling the other ones and the reports
# generation. It is itself both a raw checker and an astng checker in order
# to:
# * handle message activation / deactivation at the module level
# * handle some basic but necessary stats'data (number of classes, methods...)
#
[MASTER]
# Python code to execute, usually for sys.path manipulation such as
# pygtk.require().
#init-hook=
# Profiled execution.
profile=no
# Add <file or directory> to the black list. It should be a base name, not a
# path. You may set this option multiple times.
ignore=CVS
# Pickle collected data for later comparisons.
persistent=no
# Set the cache size for astng objects.
cache-size=500
# List of plugins (as comma separated values of python modules names) to load,
# usually to register additional checkers.
load-plugins=
[MESSAGES CONTROL]
# Enable only checker(s) with the given id(s). This option conflicts with the
# disable-checker option
#enable-checker=
# Enable all checker(s) except those with the given id(s). This option
# conflicts with the enable-checker option
disable-checker=DESIGN
# Enable all messages in the listed categories.
#enable-msg-cat=
# Disable all messages in the listed categories.
#disable-msg-cat=
# Enable the message(s) with the given id(s).
#enable-msg=
# Disable the message(s) with the given id(s).
# C0103: Invalid name
# C0111: Missing docstring
# W0142: Used * or ** magic
# W0703: Catch "Exception"
# R0902: Too many instance attributes
disable-msg=C0103,C0111,W0142,W0703,R0902
[REPORTS]
# set the output format. Available formats are text, parseable, colorized, msvs
# (visual studio) and html
output-format=text
# Include message's id in output
include-ids=yes
# Put messages in a separate file for each module / package specified on the
# command line instead of printing them on stdout. Reports (if any) will be
# written in a file name "pylint_global.[txt|html]".
files-output=no
# Tells wether to display a full report or only the messages
reports=yes
# Python expression which should return a note less than 10 (10 is the highest
# note).You have access to the variables errors warning, statement which
# respectivly contain the number of errors / warnings messages and the total
# number of statements analyzed. This is used by the global evaluation report
# (R0004).
evaluation=10.0 - ((float(5 * error + warning + refactor + convention) /
statement) * 10)
# Add a comment according to your evaluation note. This is used by the global
# evaluation report (R0004).
comment=no
# Enable the report(s) with the given id(s).
#enable-report=
# Disable the report(s) with the given id(s).
#disable-report=
# checks for :
# * doc strings
# * modules / classes / functions / methods / arguments / variables name
# * number of arguments, local variables, branchs, returns and statements in
# functions, methods
# * required module attributes
# * dangerous default values as arguments
# * redefinition of function / method / class
# * uses of the global statement
#
[BASIC]
# Required attributes for module, separated by a comma
required-attributes=
# Regular expression which should only match functions or classes name which do
# not require a docstring
# no-docstring-rgx=__.*__
# Regular expression which should only match correct module names
module-rgx=(([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+))$
# Regular expression which should only match correct module level names
const-rgx=(([A-Z_][A-Z0-9_]*)|(__.*__))$
# Regular expression which should only match correct class names
class-rgx=[A-Z_][a-zA-Z0-9]+$
# Regular expression which should only match correct function names
function-rgx=[a-z_][a-z0-9_]{2,30}$
# Regular expression which should only match correct method names
method-rgx=[a-z_][a-z0-9_]{2,30}$
# Regular expression which should only match correct instance attribute names
attr-rgx=[a-z_][a-z0-9_]{2,30}$
# Regular expression which should only match correct argument names
argument-rgx=[a-z_][a-z0-9_]{2,30}$
# Regular expression which should only match correct variable names
variable-rgx=[a-z_][a-z0-9_]{2,30}$
# Regular expression which should only match correct list comprehension /
# generator expression variable names
inlinevar-rgx=[A-Za-z_][A-Za-z0-9_]*$
# Good variable names which should always be accepted, separated by a comma
good-names=f,i,j,k,_
# Bad variable names which should always be refused, separated by a comma
# bad-names=foo,bar,baz
# List of builtins function names that should not be used, separated by a comma
bad-functions=map,filter,apply,input
# try to find bugs in the code using type inference
#
[TYPECHECK]
# Tells wether missing members accessed in mixin class should be ignored. A
# mixin class is detected if its name ends with "mixin" (case insensitive).
ignore-mixin-members=yes
# List of classes names for which member attributes should not be checked
# (useful for classes with attributes dynamicaly set).
ignored-classes=SQLObject
# When zope mode is activated, consider the acquired-members option to ignore
# access to some undefined attributes.
zope=no
# List of members which are usually get through zope's acquisition mecanism and
# so shouldn't trigger E0201 when accessed (need zope=yes to be considered).
acquired-members=REQUEST,acl_users,aq_parent
# checks for
# * unused variables / imports
# * undefined variables
# * redefinition of variable from builtins or from an outer scope
# * use of variable before assigment
#
[VARIABLES]
# Tells wether we should check for unused import in __init__ files.
init-import=no
# A regular expression matching names used for dummy variables (i.e. not used).
dummy-variables-rgx=
# List of additional names supposed to be defined in builtins. Remember that
# you should avoid to define new builtins when possible.
additional-builtins=
# checks for :
# * methods without self as first argument
# * overridden methods signature
# * access only to existant members via self
# * attributes not defined in the __init__ method
# * supported interfaces implementation
# * unreachable code
#
[CLASSES]
# List of interface methods to ignore, separated by a comma. This is used for
# instance to not check methods defines in Zope's Interface base class.
ignore-iface-methods=isImplementedBy,deferred,extends,names,namesAndDescriptions,queryDescriptionFor,getBases,getDescriptionFor,getDoc,getName,getTaggedValue,getTaggedValueTags,isEqualOrExtendedBy,setTaggedValue,isImplementedByInstancesOf,adaptWith,is_implemented_by
# List of method names used to declare (i.e. assign) instance attributes.
defining-attr-methods=__init__,__new__
# checks for sign of poor/misdesign:
# * number of methods, attributes, local variables...
# * size, complexity of functions, methods
#
[DESIGN]
# Maximum number of arguments for function / method
max-args=5
# Maximum number of locals for function / method body
max-locals=15
# Maximum number of return / yield for function / method body
max-returns=6
# Maximum number of branch for function / method body
max-branchs=12
# Maximum number of statements in function / method body
max-statements=50
# Maximum number of parents for a class (see R0901).
max-parents=7
# Maximum number of attributes for a class (see R0902).
max-attributes=7
# Minimum number of public methods for a class (see R0903).
min-public-methods=0
# Maximum number of public methods for a class (see R0904).
max-public-methods=20
# checks for
# * external modules dependencies
# * relative / wildcard imports
# * cyclic imports
# * uses of deprecated modules
#
[IMPORTS]
# Deprecated modules which should not be used, separated by a comma
deprecated-modules=regsub,string,TERMIOS,Bastion,rexec
# Create a graph of every (i.e. internal and external) dependencies in the
# given file (report R0402 must not be disabled)
import-graph=
# Create a graph of external dependencies in the given file (report R0402 must
# not be disabled)
ext-import-graph=
# Create a graph of internal dependencies in the given file (report R0402 must
# not be disabled)
int-import-graph=
# checks for :
# * unauthorized constructions
# * strict indentation
# * line length
# * use of <> instead of !=
#
[FORMAT]
# Maximum number of characters on a single line.
max-line-length=79
# Maximum number of lines in a module
max-module-lines=1000
# String used as indentation unit. This is usually " " (4 spaces) or "\t" (1
# tab).
indent-string=' '
# checks for:
# * warning notes in the code like FIXME, XXX
# * PEP 263: source code with non ascii character but no encoding declaration
#
[MISCELLANEOUS]
# List of note tags to take in consideration, separated by a comma.
notes=FIXME,XXX,TODO,BUG
# checks for similarities and duplicated code. This computation may be
# memory / CPU intensive, so you should disable it if you experiments some
# problems.
#
[SIMILARITIES]
# Minimum lines number of a similarity.
min-similarity-lines=4
# Ignore comments when computing similarities.
ignore-comments=yes
# Ignore docstrings when computing similarities.
ignore-docstrings=yes
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