Source code for cherrypy.lib.gctools

import gc
import inspect
import sys
import time

try:
    import objgraph
except ImportError:
    objgraph = None

import cherrypy
from cherrypy import _cprequest, _cpwsgi
from cherrypy.process.plugins import SimplePlugin


[docs]class ReferrerTree(object): """An object which gathers all referrers of an object to a given depth.""" peek_length = 40 def __init__(self, ignore=None, maxdepth=2, maxparents=10): self.ignore = ignore or [] self.ignore.append(inspect.currentframe().f_back) self.maxdepth = maxdepth self.maxparents = maxparents
[docs] def ascend(self, obj, depth=1): """Return a nested list containing referrers of the given object.""" depth += 1 parents = [] # Gather all referrers in one step to minimize # cascading references due to repr() logic. refs = gc.get_referrers(obj) self.ignore.append(refs) if len(refs) > self.maxparents: return [('[%s referrers]' % len(refs), [])] try: ascendcode = self.ascend.__code__ except AttributeError: ascendcode = self.ascend.im_func.func_code for parent in refs: if inspect.isframe(parent) and parent.f_code is ascendcode: continue if parent in self.ignore: continue if depth <= self.maxdepth: parents.append((parent, self.ascend(parent, depth))) else: parents.append((parent, [])) return parents
[docs] def peek(self, s): """Return s, restricted to a sane length.""" if len(s) > (self.peek_length + 3): half = self.peek_length // 2 return s[:half] + '...' + s[-half:] else: return s
def _format(self, obj, descend=True): """Return a string representation of a single object.""" if inspect.isframe(obj): filename, lineno, func, context, index = inspect.getframeinfo(obj) return "<frame of function '%s'>" % func if not descend: return self.peek(repr(obj)) if isinstance(obj, dict): return '{' + ', '.join(['%s: %s' % (self._format(k, descend=False), self._format(v, descend=False)) for k, v in obj.items()]) + '}' elif isinstance(obj, list): return '[' + ', '.join([self._format(item, descend=False) for item in obj]) + ']' elif isinstance(obj, tuple): return '(' + ', '.join([self._format(item, descend=False) for item in obj]) + ')' r = self.peek(repr(obj)) if isinstance(obj, (str, int, float)): return r return '%s: %s' % (type(obj), r)
[docs] def format(self, tree): """Return a list of string reprs from a nested list of referrers.""" output = [] def ascend(branch, depth=1): for parent, grandparents in branch: output.append((' ' * depth) + self._format(parent)) if grandparents: ascend(grandparents, depth + 1) ascend(tree) return output
[docs]def get_instances(cls): return [x for x in gc.get_objects() if isinstance(x, cls)]
[docs]class RequestCounter(SimplePlugin):
[docs] def start(self): self.count = 0
[docs] def before_request(self): self.count += 1
[docs] def after_request(self): self.count -= 1
request_counter = RequestCounter(cherrypy.engine) request_counter.subscribe()
[docs]def get_context(obj): if isinstance(obj, _cprequest.Request): return 'path=%s;stage=%s' % (obj.path_info, obj.stage) elif isinstance(obj, _cprequest.Response): return 'status=%s' % obj.status elif isinstance(obj, _cpwsgi.AppResponse): return 'PATH_INFO=%s' % obj.environ.get('PATH_INFO', '') elif hasattr(obj, 'tb_lineno'): return 'tb_lineno=%s' % obj.tb_lineno return ''
[docs]class GCRoot(object): """A CherryPy page handler for testing reference leaks.""" classes = [ (_cprequest.Request, 2, 2, 'Should be 1 in this request thread and 1 in the main thread.'), (_cprequest.Response, 2, 2, 'Should be 1 in this request thread and 1 in the main thread.'), (_cpwsgi.AppResponse, 1, 1, 'Should be 1 in this request thread only.'), ]
[docs] @cherrypy.expose def index(self): return 'Hello, world!'
[docs] @cherrypy.expose def stats(self): output = ['Statistics:'] for trial in range(10): if request_counter.count > 0: break time.sleep(0.5) else: output.append('\nNot all requests closed properly.') # gc_collect isn't perfectly synchronous, because it may # break reference cycles that then take time to fully # finalize. Call it thrice and hope for the best. gc.collect() gc.collect() unreachable = gc.collect() if unreachable: if objgraph is not None: final = objgraph.by_type('Nondestructible') if final: objgraph.show_backrefs(final, filename='finalizers.png') trash = {} for x in gc.garbage: trash[type(x)] = trash.get(type(x), 0) + 1 if trash: output.insert(0, '\n%s unreachable objects:' % unreachable) trash = [(v, k) for k, v in trash.items()] trash.sort() for pair in trash: output.append(' ' + repr(pair)) # Check declared classes to verify uncollected instances. # These don't have to be part of a cycle; they can be # any objects that have unanticipated referrers that keep # them from being collected. allobjs = {} for cls, minobj, maxobj, msg in self.classes: allobjs[cls] = get_instances(cls) for cls, minobj, maxobj, msg in self.classes: objs = allobjs[cls] lenobj = len(objs) if lenobj < minobj or lenobj > maxobj: if minobj == maxobj: output.append( '\nExpected %s %r references, got %s.' % (minobj, cls, lenobj)) else: output.append( '\nExpected %s to %s %r references, got %s.' % (minobj, maxobj, cls, lenobj)) for obj in objs: if objgraph is not None: ig = [id(objs), id(inspect.currentframe())] fname = 'graph_%s_%s.png' % (cls.__name__, id(obj)) objgraph.show_backrefs( obj, extra_ignore=ig, max_depth=4, too_many=20, filename=fname, extra_info=get_context) output.append('\nReferrers for %s (refcount=%s):' % (repr(obj), sys.getrefcount(obj))) t = ReferrerTree(ignore=[objs], maxdepth=3) tree = t.ascend(obj) output.extend(t.format(tree)) return '\n'.join(output)