3 new commits in pytest:
https://bitbucket.org/hpk42/pytest/commits/2e18fb60a375/
Changeset: 2e18fb60a375
Branch: document_ExceptionInfo_ref_cycle
User: jurko
Date: 2014-01-23 09:46:36
Summary: document explicitly clearing local references to pytest.raises()
results
pytest.raises() returns an ExceptionInfo object which, if a local reference is
made to it, forms a reference cycle:
ExceptionInfo
--> exception
--> stack frame raising the exception
--> current stack frame
--> current local variables
--> Exception Info
Such a reference cycle would then prevent any local variables in the current
stack frame, or any of its child stack frames involved in the same reference
cycle, from being garbage collected until the next reference cycle garbage
collection phase. This unnecessarily increases the program's memory footprint
and potentially slows it down.
This situation is based on a similar one described in the official 'try'
statement Python documentation for locally stored exception references.
Affected #: 1 file
diff -r 60052491d38bf3fd68909c35aa04e063415fe2b6 -r
2e18fb60a37595729a4ec9fbed78091f84a2cf20 _pytest/python.py
--- a/_pytest/python.py
+++ b/_pytest/python.py
@@ -938,6 +938,12 @@
This helper produces a ``py.code.ExceptionInfo()`` object.
+ Note that any local references made to such returned
+ ``py.code.ExceptionInfo()`` objects should be explicitly cleared, as they
+ are part of a reference cycle similar to local references to caught Python
+ exception objects. See the official Python ``try`` statement documentation
+ for more detailed information.
+
If using Python 2.5 or above, you may use this function as a
context manager::
https://bitbucket.org/hpk42/pytest/commits/89e8707d6b2f/
Changeset: 89e8707d6b2f
Branch: document_ExceptionInfo_ref_cycle
User: jurko
Date: 2014-01-23 11:36:04
Summary: reword note on explicitly clearing local references to
pytest.raises() results
Made it clearer that clearing such references is not mandatory and is only an
optional step which may help the Python interpreter speed up its garbage
collection.
Affected #: 1 file
diff -r 2e18fb60a37595729a4ec9fbed78091f84a2cf20 -r
89e8707d6b2f45a79331f5865a2a42bf11f681d3 _pytest/python.py
--- a/_pytest/python.py
+++ b/_pytest/python.py
@@ -938,12 +938,6 @@
This helper produces a ``py.code.ExceptionInfo()`` object.
- Note that any local references made to such returned
- ``py.code.ExceptionInfo()`` objects should be explicitly cleared, as they
- are part of a reference cycle similar to local references to caught Python
- exception objects. See the official Python ``try`` statement documentation
- for more detailed information.
-
If using Python 2.5 or above, you may use this function as a
context manager::
@@ -968,6 +962,22 @@
>>> raises(ZeroDivisionError, "f(0)")
<ExceptionInfo ...>
+
+ Performance note:
+ -----------------
+
+ Similar to caught exception objects in Python, explicitly clearing local
+ references to returned ``py.code.ExceptionInfo`` objects can help the
Python
+ interpreter speed up its garbage collection.
+
+ Clearing those references breaks a reference cycle (``ExceptionInfo`` -->
+ caught exception --> frame stack raising the exception --> current frame
+ stack --> local variables --> ``ExceptionInfo``) which makes Python keep
all
+ objects referenced from that cycle (including all local variables in the
+ current frame) alive until the next cyclic garbage collection run. See the
+ official Python ``try`` statement documentation for more detailed
+ information.
+
"""
__tracebackhide__ = True
if ExpectedException is AssertionError:
https://bitbucket.org/hpk42/pytest/commits/7432b6d6f51d/
Changeset: 7432b6d6f51d
User: hpk42
Date: 2014-01-23 11:42:51
Summary: Merged in jurko/pytest/document_ExceptionInfo_ref_cycle (pull
request #109)
document explicitly clearing local references to pytest.raises() results (redo
of pull request #98)
Affected #: 1 file
diff -r b96fa77ac4af935a5a7b967ab11ece8bb02e6012 -r
7432b6d6f51d935054290c8020d211eb07af485e _pytest/python.py
--- a/_pytest/python.py
+++ b/_pytest/python.py
@@ -962,6 +962,22 @@
>>> raises(ZeroDivisionError, "f(0)")
<ExceptionInfo ...>
+
+ Performance note:
+ -----------------
+
+ Similar to caught exception objects in Python, explicitly clearing local
+ references to returned ``py.code.ExceptionInfo`` objects can help the
Python
+ interpreter speed up its garbage collection.
+
+ Clearing those references breaks a reference cycle (``ExceptionInfo`` -->
+ caught exception --> frame stack raising the exception --> current frame
+ stack --> local variables --> ``ExceptionInfo``) which makes Python keep
all
+ objects referenced from that cycle (including all local variables in the
+ current frame) alive until the next cyclic garbage collection run. See the
+ official Python ``try`` statement documentation for more detailed
+ information.
+
"""
__tracebackhide__ = True
if ExpectedException is AssertionError:
Repository URL: https://bitbucket.org/hpk42/pytest/
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