[Python-checkins] CVS: python/dist/src/Lib doctest.py,1.12,1.13

2001年6月24日 13:02:49 -0700

Update of /cvsroot/python/python/dist/src/Lib
In directory usw-pr-cvs1:/tmp/cvs-serv4624/Lib
Modified Files:
	doctest.py 
Log Message:
Clear the copy of the globs dict after running examples. This helps to
break cycles, which are a special problem when running generator tests
that provoke exceptions by invoking the .next() method of a named
generator-iterator: then the iterator is named in globs, and the
iterator's frame gets a tracekback object pointing back to globs, and
gc doesn't chase these types so the cycle leaks.
Also changed _run_examples() to make a copy of globs itself, so its
callers (direct and indirect) don't have to (and changed the callers
to stop making their own copies); *that* much is a change I've been
meaning to make for a long time (it's more robust the new way).
Here's a way to provoke the symptom without doctest; it leaks at a
prodigious rate; if the last two "source" lines are replaced with
 g().next()
the iterator isn't named and then there's no leak:
source = """\
def g():
 yield 1/0
k = g()
k.next()
"""
code = compile(source, "<source>", "exec")
def f(globs):
 try:
 exec code in globs
 except ZeroDivisionError:
 pass
while 1:
 f(globals().copy())
After this change, running test_generators in an infinite loop still leaks,
but reduced from a flood to a trickle.
Index: doctest.py
===================================================================
RCS file: /cvsroot/python/python/dist/src/Lib/doctest.py,v
retrieving revision 1.12
retrieving revision 1.13
diff -C2 -r1.12 -r1.13
*** doctest.py	2001年06月24日 18:59:01	1.12
--- doctest.py	2001年06月24日 20:02:47	1.13
***************
*** 530,538 ****
 return failures, len(examples)

! # Run list of examples, in context globs. Return (#failures, #tries).

 def _run_examples(examples, globs, verbose, name):
 import sys
 saveout = sys.stdout
 try:
 sys.stdout = fakeout = _SpoofOut()
--- 530,542 ----
 return failures, len(examples)

! # Run list of examples, in a shallow copy of context (dict) globs.
! # Return (#failures, #tries).
! # CAUTION: globs is cleared before returning. This is to help break
! # cycles that may have been created by the examples.

 def _run_examples(examples, globs, verbose, name):
 import sys
 saveout = sys.stdout
+ globs = globs.copy()
 try:
 sys.stdout = fakeout = _SpoofOut()
***************
*** 541,544 ****
--- 545,555 ----
 finally:
 sys.stdout = saveout
+ # While Python gc can clean up most cycles on its own, it doesn't
+ # chase frame objects. This is especially irksome when running
+ # generator tests that raise exceptions, because a named generator-
+ # iterator gets an entry in globs, and the generator-iterator
+ # object's frame's traceback info points back to globs. This is
+ # easy to break just by clearing the namespace.
+ globs.clear()
 return x

***************
*** 546,550 ****
 """f, globs, verbose=0, name="NoName" -> run examples from f.__doc__.

! Use dict globs as the globals for execution.
 Return (#failures, #tries).

--- 557,561 ----
 """f, globs, verbose=0, name="NoName" -> run examples from f.__doc__.

! Use (a shallow copy of) dict globs as the globals for execution.
 Return (#failures, #tries).

***************
*** 736,740 ****
 e = _extract_examples(s)
 if e:
! f, t = _run_examples(e, self.globs.copy(), self.verbose, name)
 if self.verbose:
 print f, "of", t, "examples failed in string", name
--- 747,751 ----
 e = _extract_examples(s)
 if e:
! f, t = _run_examples(e, self.globs, self.verbose, name)
 if self.verbose:
 print f, "of", t, "examples failed in string", name
***************
*** 774,779 ****
 if self.verbose:
 print "Running", name + ".__doc__"
! f, t = run_docstring_examples(object, self.globs.copy(),
! self.verbose, name)
 if self.verbose:
 print f, "of", t, "examples failed in", name + ".__doc__"
--- 785,789 ----
 if self.verbose:
 print "Running", name + ".__doc__"
! f, t = run_docstring_examples(object, self.globs, self.verbose, name)
 if self.verbose:
 print f, "of", t, "examples failed in", name + ".__doc__"