bpo-29564: warnings suggests to enable tracemalloc (GH-10486) (GH-10509)
The warnings module now suggests to enable tracemalloc if the source
is specified, tracemalloc module is available, but tracemalloc is not
tracing memory allocations.
(cherry picked from commit 2c07c493d2eb45101312e3eb3a77f94d0c9cad1f)
Co-authored-by: Victor Stinner <vstinner@redhat.com>
diff --git a/Lib/warnings.py b/Lib/warnings.py
index 81f9864..ae4295e 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -33,9 +33,8 @@
pass
def _formatwarnmsg_impl(msg):
- s = ("%s:%s: %s: %s\n"
- % (msg.filename, msg.lineno, msg.category.__name__,
- msg.message))
+ category = msg.category.__name__
+ s = f"{msg.filename}:{msg.lineno}: {category}: {msg.message}\n"
if msg.line is None:
try:
@@ -55,11 +54,20 @@
if msg.source is not None:
try:
import tracemalloc
- tb = tracemalloc.get_object_traceback(msg.source)
+ # Logging a warning should not raise a new exception:
+ # catch Exception, not only ImportError and RecursionError.
except Exception:
- # When a warning is logged during Python shutdown, tracemalloc
- # and the import machinery don't work anymore
+ # 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'
@@ -77,6 +85,9 @@
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')
return s
# Keep a reference to check if the function was replaced