STINNER Victor <vstin...@redhat.com> added the comment:
You can implement this behavior using the new sys.unraisablehook (Python 3.8):
---
import sys
import tracemalloc
def foo():
open('foo', 'wb')
def hook(unraisable):
orig_unraisablehook(unraisable)
if unraisable.object is not None:
tb = tracemalloc.get_object_traceback(unraisable.object)
if tb:
print("Object allocated at:")
for line in tb:
print(line)
orig_unraisablehook = sys.unraisablehook
sys.unraisablehook = hook
tracemalloc.start(5)
foo()
---
Output:
---
Exception ignored in: <_io.FileIO name='foo' mode='wb' closefd=True>
Traceback (most recent call last):
File "foo.py", line 5, in foo
open('foo', 'wb')
ResourceWarning: unclosed file <_io.BufferedWriter name='foo'>
Object allocated at:
foo.py:21
foo.py:5
---
I understand that this issue is about modifying
_PyErr_WriteUnraisableDefaultHook() in Python/errors.c (it's written in C) to
implement the same logic than the default implementation of
warnings._formatwarnmsg() when formatting a ResourceWarning with the source
object:
try:
import tracemalloc
# Logging a warning should not raise a new exception:
# catch Exception, not only ImportError and RecursionError.
except Exception:
# don't suggest to enable tracemalloc if it's not available
tracing = True
tb = None
else:
tracing = tracemalloc.is_tracing()
try:
tb = tracemalloc.get_object_traceback(msg.source)
except Exception:
# When a warning is logged during Python shutdown, tracemalloc
# and the import machinery don't work anymore
tb = None
if tb is not None:
s += 'Object allocated at (most recent call last):\n'
for frame in tb:
s += (' File "%s", lineno %s\n'
% (frame.filename, frame.lineno))
try:
if linecache is not None:
line = linecache.getline(frame.filename, frame.lineno)
else:
line = None
except Exception:
line = None
if line:
line = line.strip()
s += ' %s\n' % line
elif not tracing:
s += (f'{category}: Enable tracemalloc to get the object '
f'allocation traceback\n')
In C, _PyTraceMalloc_GetTraceback() can be used to retrieve the traceback of an
object saved by tracemalloc.
See also _PyMem_DumpTraceback() used to log the tracemaltoc when Python detects
a buffer overflow:
https://pythondev.readthedocs.io/debug_tools.html#debug-memory-errors
----------
nosy: +vstinner
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue37350>
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