asyncio, Tulip issue 137: In debug mode, save traceback where Future, Task and
Handle objects are created. Pass the traceback to call_exception_handler() in
the 'source_traceback' key.
The traceback is truncated to hide internal calls in asyncio, show only the
traceback from user code.
Add tests for the new source_traceback, and a test for the 'Future/Task
exception was never retrieved' log.
diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index b127142..90115e5 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -21,6 +21,7 @@
import logging
import socket
import subprocess
+import traceback
import time
import os
import sys
@@ -290,7 +291,10 @@
Any positional arguments after the callback will be passed to
the callback when it is called.
"""
- return self.call_at(self.time() + delay, callback, *args)
+ timer = self.call_at(self.time() + delay, callback, *args)
+ if timer._source_traceback:
+ del timer._source_traceback[-1]
+ return timer
def call_at(self, when, callback, *args):
"""Like call_later(), but uses an absolute time."""
@@ -299,6 +303,8 @@
if self._debug:
self._assert_is_current_event_loop()
timer = events.TimerHandle(when, callback, args, self)
+ if timer._source_traceback:
+ del timer._source_traceback[-1]
heapq.heappush(self._scheduled, timer)
return timer
@@ -312,7 +318,10 @@
Any positional arguments after the callback will be passed to
the callback when it is called.
"""
- return self._call_soon(callback, args, check_loop=True)
+ handle = self._call_soon(callback, args, check_loop=True)
+ if handle._source_traceback:
+ del handle._source_traceback[-1]
+ return handle
def _call_soon(self, callback, args, check_loop):
if tasks.iscoroutinefunction(callback):
@@ -320,6 +329,8 @@
if self._debug and check_loop:
self._assert_is_current_event_loop()
handle = events.Handle(callback, args, self)
+ if handle._source_traceback:
+ del handle._source_traceback[-1]
self._ready.append(handle)
return handle
@@ -344,6 +355,8 @@
def call_soon_threadsafe(self, callback, *args):
"""Like call_soon(), but thread safe."""
handle = self._call_soon(callback, args, check_loop=False)
+ if handle._source_traceback:
+ del handle._source_traceback[-1]
self._write_to_self()
return handle
@@ -757,7 +770,14 @@
for key in sorted(context):
if key in {'message', 'exception'}:
continue
- log_lines.append('{}: {!r}'.format(key, context[key]))
+ value = context[key]
+ if key == 'source_traceback':
+ tb = ''.join(traceback.format_list(value))
+ value = 'Object created at (most recent call last):\n'
+ value += tb.rstrip()
+ else:
+ value = repr(value)
+ log_lines.append('{}: {}'.format(key, value))
logger.error('\n'.join(log_lines), exc_info=exc_info)