[issue29908] Inconsistent crashing with an access violation

[Steve Dower]

Steve Dower added the comment:

Thanks for the link! I've reported it to the C Runtime team and they'll get it 
fixed. (Because this is an operating system component, the fix will come 
through normal Windows Updates and apply to any version of Python 3.5+, so I'd 
rather not build a workaround into the product for it.)

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[issue29908] Inconsistent crashing with an access violation

[Eryk Sun]

Eryk Sun added the comment:

I can confirm that the CRT function construct_environment_block() does cause an 
access violation sometimes when no "=x:" shell variables are defined in the 
current environment. These "=x:" environment variables are the way that Windows 
emulates DOS per-drive working directories in a shell. The API itself never 
sets these variables; it only uses them if they're defined.

You should be able to avoid this bug by defining the environment variable 
"=C:". The simplest way to do this in Python is via os.chdir. For example:

import os

cwd = os.getcwd()
try:
os.chdir('C:')
finally:
os.chdir(cwd)

The implementation of os.chdir calls SetCurrentDirectoryW, which, for a 
drive-relative path such as "C:", will first look for an "=x:" environment 
variable and otherwise default to the root directory. After it changes the 
process current working directory, chdir() calls GetCurrentDirectoryW and 
SetEnvironmentVariableW to set the new value of the "=x:" variable.

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[issue29908] Inconsistent crashing with an access violation

[Cameron Mckain]

Cameron Mckain added the comment:

See this here: 
https://wpdev.uservoice.com/forums/110705-universal-windows-platform/suggestions/18355615-ucrtbase-bug-wspawnve-is-broken

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[issue29908] Inconsistent crashing with an access violation

[Steve Dower]

Steve Dower added the comment:

I was thinking of a Django issue. It'd be nice to know what they fixed that 
prevents the problem occurring.

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[issue29908] Inconsistent crashing with an access violation

[Cameron Mckain]

Cameron Mckain added the comment:

No, my PyCharm issue has not been responded to by any of their people. Here is 
the link: https://youtrack.jetbrains.com/issue/PY-23297 
Also, I have uploaded a screenshot of VS's debugging of the crash if it will be 
helpful.

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Added file: http://bugs.python.org/file46760/Desctop screenshot.png

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[issue29908] Inconsistent crashing with an access violation

[Steve Dower]

Steve Dower added the comment:

Do you have a reference to an issue from their side about this? Python should 
never crash due to pure Python code, so we'd like to be able to prevent this in 
the future.

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[issue29908] Inconsistent crashing with an access violation

[Cameron Mckain]

Cameron Mckain added the comment:

The problem was fixed after updating to Django 1.11; apparently, Django 1.10 is 
not fully compatible with Python 3.6. Thanks for your time.

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

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[issue29908] Inconsistent crashing with an access violation

[Eryk Sun]

Eryk Sun added the comment:

Steve, I added 3.5 because the crash involved ucrtbase.dll. I'll remove it for 
now since the problem is only confirmed in 3.6.

Offset 0x3bd9e in 32-bit ucrtbase.dll is in wdupenv_s [1]. It's probably from 
calling new_spawnve in pydev_monkey.py, as shown in the faulthandler output. I 
don't use PyCharm, so I can't confirm this, but we know wdupenv_s is called by 
the CRT's wspawnve function. For example:

>>> os.spawnve(os.P_WAIT, sys.executable, ['python', '-V'], os.environ)

Breakpoint 0 hit
eax=01b412b0 ebx= ecx=01b41280 edx=01b412b2 esi=01b41280 
edi=
eip=7672bd9e esp=013ef368 ebp=013ef380 iopl=0 nv up ei pl nz na po 
nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b 
efl=0202
ucrtbase!wdupenv_s+0x18e:
7672bd9e 668b08  mov cx,word ptr [eax]
ds:002b:01b412b0=0070
0:000> kc 7
ucrtbase!wdupenv_s
ucrtbase!wsearchenv_s
ucrtbase!wspawnlpe
ucrtbase!wspawnlpe
ucrtbase!wspawnve
python36!os_spawnve_impl
python36!os_spawnve

[1]: https://msdn.microsoft.com/en-us/library/ms175774.aspx

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versions:  -Python 3.5

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[issue29908] Inconsistent crashing with an access violation

[Steve Dower]

Steve Dower added the comment:

Have you confirmed this occurring with 3.5? PyCharm has a very invasive 
debugger that is almost certainly responsible, but there's a significant 
difference between the 3.5 and 3.6 implementations that is probably relevant.

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[issue29908] Inconsistent crashing with an access violation

[Cameron Mckain]

Cameron Mckain added the comment:

C:\Users\cmcka\PycharmProjects\test>wevtutil qe application /rd:true /c:1 
/format:text /q:"*[System[Provider[@Name='Application 
Error']]][EventData[Data='python.exe'][Data='ucrtbase.dll']]"
Event[0]:
  Log Name: Application
  Source: Application Error
  Date: 2017-03-26T01:46:20.230
  Event ID: 1000
  Task: Application Crashing Events
  Level: Error
  Opcode: Info
  Keyword: Classic
  User: N/A
  User Name: N/A
  Computer: CAMERON-OMEN
  Description:
Faulting application name: python.exe, version: 3.6.1150.1013, time stamp: 
0x58d169bd
Faulting module name: ucrtbase.dll, version: 10.0.14393.0, time stamp: 
0x57898db2
Exception code: 0xc005
Fault offset: 0x0003bd9e
Faulting process id: 0x4464
Faulting application start time: 0x01d2a60d6fdf23d2
Faulting application path: C:\Python36\python.exe
Faulting module path: C:\windows\System32\ucrtbase.dll
Report Id: 109058c0-4e02-4bb6-a799-d6a975fe0d6f
Faulting package full name:
Faulting package-relative application ID:

This is from Python's faulthandler as well:
Windows fatal exception: access violation

Thread 0x44b0 (most recent call first):
  File 
"C:\Users\cmcka\AppData\Local\JetBrains\Toolbox\apps\PyCharm-P\ch-0\171.3780.115\helpers\pydev\pydevd.py",
 line 96 in _on_run
  File 
"C:\Users\cmcka\AppData\Local\JetBrains\Toolbox\apps\PyCharm-P\ch-0\171.3780.115\helpers\pydev\_pydevd_bundle\pydevd_comm.py",
 line 291 in run
  File "C:\Python36\lib\threading.py", line 916 in _bootstrap_inner
  File "C:\Python36\lib\threading.py", line 884 in _bootstrap

Thread 0x44ac (most recent call first):
  File 
"C:\Users\cmcka\AppData\Local\JetBrains\Toolbox\apps\PyCharm-P\ch-0\171.3780.115\helpers\pydev\_pydevd_bundle\pydevd_comm.py",
 line 353 in _on_run
  File 
"C:\Users\cmcka\AppData\Local\JetBrains\Toolbox\apps\PyCharm-P\ch-0\171.3780.115\helpers\pydev\_pydevd_bundle\pydevd_comm.py",
 line 291 in run
  File "C:\Python36\lib\threading.py", line 916 in _bootstrap_inner
  File "C:\Python36\lib\threading.py", line 884 in _bootstrap

Thread 0x39d4 (most recent call first):
  File "C:\Python36\lib\threading.py", line 299 in wait
  File "C:\Python36\lib\queue.py", line 173 in get
  File 
"C:\Users\cmcka\AppData\Local\JetBrains\Toolbox\apps\PyCharm-P\ch-0\171.3780.115\helpers\pydev\_pydevd_bundle\pydevd_comm.py",
 line 430 in _on_run
  File 
"C:\Users\cmcka\AppData\Local\JetBrains\Toolbox\apps\PyCharm-P\ch-0\171.3780.115\helpers\pydev\_pydevd_bundle\pydevd_comm.py",
 line 291 in run
  File "C:\Python36\lib\threading.py", line 916 in _bootstrap_inner
  File "C:\Python36\lib\threading.py", line 884 in _bootstrap

Current thread 0x446c (most recent call first):
  File 
"C:\Users\cmcka\AppData\Local\JetBrains\Toolbox\apps\PyCharm-P\ch-0\171.3780.115\helpers\pydev\_pydev_bundle\pydev_monkey.py",
 line 380 in new_spawnve
  File "C:\Python36\lib\site-packages\django\utils\autoreload.py", line 290 in 
restart_with_reloader
  File "C:\Python36\lib\site-packages\django\utils\autoreload.py", line 304 in 
python_reloader
  File "C:\Python36\lib\site-packages\django\utils\autoreload.py", line 333 in 
main
  File 
"C:\Python36\lib\site-packages\django\core\management\commands\runserver.py", 
line 106 in run
  File 
"C:\Python36\lib\site-packages\django\core\management\commands\runserver.py", 
line 97 in handle
  File "C:\Python36\lib\site-packages\django\core\management\base.py", line 345 
in execute
  File 
"C:\Python36\lib\site-packages\django\core\management\commands\runserver.py", 
line 58 in execute
  File "C:\Python36\lib\site-packages\django\core\management\base.py", line 294 
in run_from_argv
  File "C:\Python36\lib\site-packages\django\core\management\__init__.py", line 
359 in execute
  File "C:\Python36\lib\site-packages\django\core\management\__init__.py", line 
367 in execute_from_command_line
  File "C:/Users/cmcka/PycharmProjects/test/manage.py", line 22 in 
  File 
"C:\Users\cmcka\AppData\Local\JetBrains\Toolbox\apps\PyCharm-P\ch-0\171.3780.115\helpers\pydev\_pydev_imps\_pydev_execfile.py",
 line 18 in execfile
  File 
"C:\Users\cmcka\AppData\Local\JetBrains\Toolbox\apps\PyCharm-P\ch-0\171.3780.115\helpers\pydev\pydevd.py",
 line 1015 in run
  File 
"C:\Users\cmcka\AppData\Local\JetBrains\Toolbox\apps\PyCharm-P\ch-0\171.3780.115\helpers\pydev\pydevd.py",
 line 1578 in 

Process finished with exit code -1073741819 (0xC005)

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[issue29908] Inconsistent crashing with an access violation

[Eryk Sun]

Eryk Sun added the comment:

The offset in ucrtbase.dll where it's crashing may hint at the culprit. The 
following command should print the full event log for the most recent crash:

wevtutil qe application /rd:true /c:1 /format:text 
/q:"*[System[Provider[@Name='Application 
Error']]][EventData[Data='python.exe'][Data='ucrtbase.dll']]"

--
components: +Windows
nosy: +eryksun, paul.moore, steve.dower, tim.golden, zach.ware
versions: +Python 3.5, Python 3.6, Python 3.7

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[issue29908] Inconsistent crashing with an access violation

[Cameron Mckain]

Changes by Cameron Mckain :


--
type:  -> crash

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[issue29908] Inconsistent crashing with an access violation

[Cameron Mckain]

New submission from Cameron Mckain:

Almost every time I attempt to run my Django server ("python manage.py 
runserver") from PyCharm, python.exe crashes with the error "Unhandled 
exception at 0x7647BD9E (ucrtbase.dll) in python.exe: 0xC005: Access 
violation reading location 0x03BF8000." and "Process finished with exit code 
-1073741819 (0xC005)" is printed in the console. These errors only happen 
about 90% of the time.

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messages: 290504
nosy: Cameron Mckain
priority: normal
severity: normal
status: open
title: Inconsistent crashing with an access violation

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