Import a variant of zope.testing's TrackRefs class, helpful in tracking down leaks.

src/supervisor/tests/trackrefs.py

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+##############################################################################
+#
+# Copyright (c) 2007 Zope Corporation and Contributors.
+# All Rights Reserved.
+#
+# This software is subject to the provisions of the Zope Public License,
+# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
+# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
+# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
+# FOR A PARTICULAR PURPOSE
+#
+##############################################################################
+
+""" Code from the zope.testing module to help track down memory leaks
+
+TrackRefs works only in a python compiled with the --with-pydebug flag.
+An example of how to use TrackRefs in a function is below.
+
+glen = 0
+rc = 0
+
+def doit():
+    newglen = gc.collect()
+    global glen
+    if newglen > glen:
+        print
+        print "-------------------------------------"
+        print "more garbage", newglen - glen
+        glen = newglen
+        print "-------------------------------------"
+        print
+    if refs:
+        newrc = sys.gettotalrefcount()
+        global rc
+        if newrc > rc:
+            refs.update()
+            refs.detailed_refcounts(newrc, rc)
+        rc = newrc
+"""
+
+import sys
+import gc
+import types
+
+class TrackRefs(object):
+    """Object to track reference counts across test runs."""
+
+    def __init__(self):
+        self.type2count = {}
+        self.type2all = {}
+        self.delta = None
+        self.n = 0
+        self.update()
+        self.delta = None
+
+    def update(self):
+        gc.collect()
+        obs = sys.getobjects(0)
+        type2count = {}
+        type2all = {}
+        n = 0
+        for o in obs:
+            if type(o) is str and o == '<dummy key>':
+                # avoid dictionary madness
+                continue
+
+            all = sys.getrefcount(o) - 3
+            n += all
+
+            t = type(o)
+            if t is types.InstanceType:
+                t = o.__class__
+
+            if t in type2count:
+                type2count[t] += 1
+                type2all[t] += all
+            else:
+                type2count[t] = 1
+                type2all[t] = all
+
+
+        ct = [(
+               type_or_class_title(t),
+               type2count[t] - self.type2count.get(t, 0),
+               type2all[t] - self.type2all.get(t, 0),
+               )
+              for t in type2count.iterkeys()]
+        ct += [(
+                type_or_class_title(t),
+                - self.type2count[t],
+                - self.type2all[t],
+                )
+               for t in self.type2count.iterkeys()
+               if t not in type2count]
+        ct.sort()
+        self.delta = ct
+        self.type2count = type2count
+        self.type2all = type2all
+        self.n = n
+
+
+    def output(self):
+        printed = False
+        s1 = s2 = 0
+        for t, delta1, delta2 in self.delta:
+            if delta1 or delta2:
+                if not printed:
+                    print (
+                        '    Leak details, changes in instances and refcounts'
+                        ' by type/class:')
+                    print "    %-55s %6s %6s" % ('type/class', 'insts', 'refs')
+                    print "    %-55s %6s %6s" % ('-' * 55, '-----', '----')
+                    printed = True
+                print "    %-55s %6d %6d" % (t, delta1, delta2)
+                s1 += delta1
+                s2 += delta2
+
+        if printed:
+            print "    %-55s %6s %6s" % ('-' * 55, '-----', '----')
+            print "    %-55s %6s %6s" % ('total', s1, s2)
+
+
+        self.delta = None
+
+    def detailed_refcounts(self, rc, prev):
+        """Report a change in reference counts, with extra detail."""
+        print ("  sum detail refcount=%-8d"
+               " sys refcount=%-8d"
+               " change=%-6d"
+               % (self.n, rc, rc - prev))
+        self.output()
+
+def type_or_class_title(t):
+    module = getattr(t, '__module__', '__builtin__')
+    if module == '__builtin__':
+        return t.__name__
+    return "%s.%s" % (module, t.__name__)
+