New submission from Anthony Sottile <asott...@umich.edu>:
```
import multiprocessing
class E(Exception):
def __init__(self, a1, a2):
Exception.__init__(self, '{}{}'.format(a1, a2))
def f(_):
raise E(1, 2)
multiprocessing.Pool(1).map(f, (1,))
```
Running this causes a hang:
```
$ python3.7 t2.py
Exception in thread Thread-3:
Traceback (most recent call last):
File "/usr/lib/python3.7/threading.py", line 917, in _bootstrap_inner
self.run()
File "/usr/lib/python3.7/threading.py", line 865, in run
self._target(*self._args, **self._kwargs)
File "/usr/lib/python3.7/multiprocessing/pool.py", line 496, in
_handle_results
task = get()
File "/usr/lib/python3.7/multiprocessing/contrnection.py", line 251, in recv
return _ForkingPickler.loads(buf.getbuffer())
TypeError: __init__() missing 1 required positional argument: 'a2'
```
Upon eventual `^C`
```
^CTraceback (most recent call last):
Process ForkPoolWorker-1:
File "t2.py", line 10, in <module>
multiprocessing.Pool(1).map(f, (1,))
File "/usr/lib/python3.7/multiprocessing/pool.py", line 290, in map
return self._map_async(func, iterable, mapstar, chunksize).get()
File "/usr/lib/python3.7/multiprocessing/pool.py", line 677, in get
self.wait(timeout)
File "/usr/lib/python3.7/multiprocessing/pool.py", line 674, in wait
Traceback (most recent call last):
File "/usr/lib/python3.7/multiprocessing/process.py", line 297, in _bootstrap
self.run()
File "/usr/lib/python3.7/multiprocessing/process.py", line 99, in run
self._target(*self._args, **self._kwargs)
File "/usr/lib/python3.7/multiprocessing/pool.py", line 110, in worker
task = get()
File "/usr/lib/python3.7/multiprocessing/queues.py", line 352, in get
res = self._reader.recv_bytes()
File "/usr/lib/python3.7/multiprocessing/connection.py", line 216, in
recv_bytes
buf = self._recv_bytes(maxlength)
File "/usr/lib/python3.7/multiprocessing/connection.py", line 407, in
_recv_bytes
buf = self._recv(4)
File "/usr/lib/python3.7/multiprocessing/connection.py", line 379, in _recv
chunk = read(handle, remaining)
KeyboardInterrupt
self._event.wait(timeout)
File "/usr/lib/python3.7/threading.py", line 552, in wait
signaled = self._cond.wait(timeout)
File "/usr/lib/python3.7/threading.py", line 296, in wait
waiter.acquire()
KeyboardInterrupt
Traceback (most recent call last):
File "/usr/lib/python3.7/multiprocessing/util.py", line 265, in
_run_finalizers
finalizer()
File "/usr/lib/python3.7/multiprocessing/util.py", line 189, in __call__
res = self._callback(*self._args, **self._kwargs)
File "/usr/lib/python3.7/multiprocessing/pool.py", line 611, in
_terminate_pool
"Cannot have cache with result_hander not alive")
AssertionError: Cannot have cache with result_hander not alive
```
(I've also tried this against master@158695817d736df8b18682866033c87e46252309)
----------
components: Library (Lib)
messages: 330397
nosy: Anthony Sottile
priority: normal
severity: normal
status: open
title: exception unpickling error causes `multiprocessing.Pool` to hang forever
versions: Python 3.7, Python 3.8
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue35311>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
