[issue37677] Seg Fault on OSX when multiprocessing

[Ronald Oussoren]

Ronald Oussoren  added the comment:

I'm closing this issue because this crash is caused by a platform issue, and 
Python 3.8 has a workaround by using a different spawn method in 
multiprocessing.

--
resolution:  -> out of date
stage:  -> resolved
status: open -> closed

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[issue37677] Seg Fault on OSX when multiprocessing

[Ronald Oussoren]

Ronald Oussoren  added the comment:

Looking at the stack trace this is a similar issue as the "no_proxy" one, but 
in some sense worse because it happens when just calling a regular unix API 
(not an Apple framework API).

The first few lines of the stack trace are for code in the "Network" framework 
which is new in macOS 10.14 and is based on lib dispatch and  hence uses 
threads. That results in the same problem as the "no_proxy" one: code that 
causes problems when called after os.fork().

That's a bug in macOS.

In Python 3.8 the multiprocessing module switched to "spawn" mode instead of 
"fork" mode because of this.  You can do this manually for earlier versions 
(https://docs.python.org/3.7/library/multiprocessing.html#contexts-and-start-methods)

P.S. A reproducer would still be nice as that would make it easier to raise and 
issue with Apple about this.

--
components: +macOS
nosy: +ned.deily, ronaldoussoren
versions: +Python 3.6

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[issue37677] Seg Fault on OSX when multiprocessing

[Timothy Stonis]

Timothy Stonis  added the comment:

Hi, I have the exact same issue and same stack trace from getaddrinfo (except 
Python 2.7). Same as original poster, it only happens every couple of weeks and 
I don't know how to reproduce. For me it's in an Odoo instance that spawns 
multiple workers with connections to a postgres database. I think this is a 
MacOS bug, since the issue does not happen on High Sierra (10.13).

--
nosy: +timstonis
versions: +Python 2.7 -Python 3.6

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[issue37677] Seg Fault on OSX when multiprocessing

[alvis]

alvis  added the comment:

Hi, sorry i am unable to provide a standalone script that cause this issue, as 
it happen once every few weeks. Is it similar to the no_proxy=* issue?

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[issue37677] Seg Fault on OSX when multiprocessing

[Karthikeyan Singaravelan]

Karthikeyan Singaravelan  added the comment:

Thanks for the report. It would be helpful to have a standalone reproducer for 
this issue to try reproducing it in 3.6 and other versions.

--
nosy: +davin, pitrou, xtreak

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[issue37677] Seg Fault on OSX when multiprocessing

[alvis]

New submission from alvis :

Encountered a crash with the following logs.
I have already added no_proxy=*, and it fixed the issue which i can replicate 
consistent. However, this crash does not happen every time, maybe once in a few 
week.

Process:   Python [66435]
Path:  
/Library/Frameworks/Python.framework/Versions/3.6/Resources/Python.app/Contents/MacOS/Python
Identifier:Python
Version:   3.6.8 (3.6.8)
Code Type: X86-64 (Native)
Parent Process:Python [65077]
Responsible:   Python [66435]
User ID:   501

Date/Time: 2019-07-24 21:45:29.722 +0800
OS Version:Mac OS X 10.14.2 (18C54)
Report Version:12
Bridge OS Version: 3.5 (16P5125)
Anonymous UUID:3F729BF3-2BB1-3830-B6FE-D22CA431DE5A


Time Awake Since Boot: 160 seconds

System Integrity Protection: enabled

Crashed Thread:2

Exception Type:EXC_BAD_ACCESS (SIGSEGV)
Exception Codes:   KERN_INVALID_ADDRESS at 0x000109b23aa2
Exception Note:EXC_CORPSE_NOTIFY

Termination Signal:Segmentation fault: 11
Termination Reason:Namespace SIGNAL, Code 0xb
Terminating Process:   exc handler [66435]

VM Regions Near 0x109b23aa2:
MALLOC_LARGE   000109aa3000-000109b23000 [  512K] rw-/rwx 
SM=COW  
--> 
__TEXT 000109b27000-000109b3d000 [   88K] r-x/rwx 
SM=COW  
/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/numpy/.dylibs/libgcc_s.1.dylib

Application Specific Information:
*** multi-threaded process forked ***
crashed on child side of fork pre-exec 

Thread 2 Crashed:
0   libsystem_trace.dylib   0x7fff7d6fdab3 _os_log_cmp_key + 4
1   libsystem_c.dylib   0x7fff7d5aaa5e rb_tree_find_node + 
53
2   libsystem_trace.dylib   0x7fff7d6fbc81 os_log_create + 370
3   libnetwork.dylib0x7fff7c04058f 
nwlog_legacy_init_once + 47
4   libsystem_pthread.dylib 0x7fff7d6e1ce4 
__pthread_once_handler + 66
5   libsystem_platform.dylib0x7fff7d6d7acb _os_once_callout + 18
6   libsystem_pthread.dylib 0x7fff7d6e1c7f pthread_once + 56
7   libnetwork.dylib0x7fff7c024ccd 
networkd_settings_init + 669
8   libnetwork.dylib0x7fff7c024982 
networkd_settings_get_bool + 18
9   libnetwork.dylib0x7fff7c0244f0 
-[NWConcrete_nw_parameters initWithStack:] + 160
10  libnetwork.dylib0x7fff7c023d97 
nw_path_create_evaluator_for_endpoint + 487
11  libnetwork.dylib0x7fff7c2451bc 
nw_nat64_v4_address_requires_synthesis + 220
12  libsystem_info.dylib0x7fff7d609e83 
_gai_nat64_v4_address_requires_synthesis + 67
13  libsystem_info.dylib0x7fff7d609210 
_gai_nat64_second_pass + 512
14  libsystem_info.dylib0x7fff7d5e7b4a si_addrinfo + 1978
15  libsystem_info.dylib0x7fff7d5e7262 
_getaddrinfo_internal + 242
16  libsystem_info.dylib0x7fff7d5e715d getaddrinfo + 61
17  _socket.cpython-36m-darwin.so   0x0001092c24ed socket_getaddrinfo + 
621
18  org.python.python   0x000106d63697 
_PyCFunction_FastCallDict + 183
19  org.python.python   0x000106de5747 call_function + 439
20  org.python.python   0x000106de1eb7 
_PyEval_EvalFrameDefault + 27559
21  org.python.python   0x000106de61af 
_PyEval_EvalCodeWithName + 2447
22  org.python.python   0x000106de6ae1 fast_function + 545
23  org.python.python   0x000106de5721 call_function + 401
24  org.python.python   0x000106de1eb7 
_PyEval_EvalFrameDefault + 27559
25  org.python.python   0x000106de61af 
_PyEval_EvalCodeWithName + 2447
26  org.python.python   0x000106de6ae1 fast_function + 545
27  org.python.python   0x000106de5721 call_function + 401
28  org.python.python   0x000106de1eb7 
_PyEval_EvalFrameDefault + 27559
29  org.python.python   0x000106de6a3d fast_function + 381
30  org.python.python   0x000106de5721 call_function + 401
31  org.python.python   0x000106de1eb7 
_PyEval_EvalFrameDefault + 27559
32  org.python.python   0x000106de61af 
_PyEval_EvalCodeWithName + 2447
33  org.python.python   0x000106de6ae1 fast_function + 545
34  org.python.python   0x000106de5721 call_function + 401
35  org.python.python   0x000106de1eb7 
_PyEval_EvalFrameDefault + 27559
36  org.python.python   0x000106de61af 
_PyEval_EvalCodeWithName + 2447
37  org.python.python   0x000106de6dfb