[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Barry A. Warsaw]

Barry A. Warsaw  added the comment:

Closing in favor of issue33725

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stage:  -> resolved
status: open -> closed

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Davin Potts]

Davin Potts  added the comment:

Resolution is marked dupe but status is still open.  Are we closing this one or 
is there a more specific remedy for this situation (as opposed to what 
issue33725 discusses) that would be helpful to document?

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nosy: +davin

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Barry A. Warsaw]

Barry A. Warsaw  added the comment:

I am going to dupe this to 33725 after all.

--
resolution:  -> duplicate
superseder:  -> High Sierra hang when using multi-processing

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Barry A. Warsaw]

Barry A. Warsaw  added the comment:

Nope, actually double fork doesn't work.  It's misleading because in my 
testing, the first invocation of the process causes the core dump, but 
subsequent runs do not.

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Barry A. Warsaw]

Barry A. Warsaw  added the comment:

I'm still testing this solution, but it looks like if you set the environment 
variable, and then double fork, the granchild won't crash.  Roughly:

os.putenv('OBJC_DISABLE_INITIALIZE_FORK_SAFETY', 'YES')
pid = os.fork()
if pid == 0:
subpid = os.fork()
if subpid == 0:
# I'm in a safe grandchild

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Barry A. Warsaw]

Barry A. Warsaw  added the comment:

Based on my testing, the environment variable has to be set before the parent 
process starts.  Neither os.environ nor os.putenv seem to do the trick.

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Barry A. Warsaw]

Barry A. Warsaw  added the comment:

I've done a fair bit of testing and it seems rather inconsistent as to whether 
either of these work when added right before an explicit call to `os.fork()`:

os.environ['OBJC_DISABLE_INITIALIZE_FORK_SAFETY'] = 'YES'

ctyles.cdll.LoadLibrary('/System/Library/Frameworks/Foundation.framework/Foundation')

Neither of these seems to reliably prevent the __NSPlaceholderDate warning, nor 
prevent the core dumps.  The best I've been able to do is to prevent them by 
setting the environment variable *before* the parent process starts (i.e. 
outside of the Python code of the process).

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Barry A. Warsaw]

Barry A. Warsaw  added the comment:

I'm not sure whether it's a duplicate or not, since in my case it doesn't hang, 
but instead core dumps.  It's seems like the reasoning given in the Ruby bug is 
relevant to Python too, so maybe we should adopt the same workaround.  For our 
internal projects, I'm probably just going to set the environment variable for 
now.

I'd love to know what Ned and Ronald thing, thus cc'ing them.

--
nosy: +ned.deily, ronaldoussoren

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Pablo Galindo Salgado]

Pablo Galindo Salgado  added the comment:

This can a duplicate of https://bugs.python.org/issue33725

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Pablo Galindo Salgado]

Pablo Galindo Salgado  added the comment:

Apparently, GitLab have a more permanent solution around this by enabling the 
Objective-C runtime before any forking happens: 

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/16649/diffs

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Barry A. Warsaw]

Barry A. Warsaw  added the comment:

On Nov 12, 2018, at 13:34, Pablo Galindo Salgado  wrote:

> Apparently setting the env variable OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES 
> should fix some fork-related changes. Have you tried already doing this? Does 
> it change the behaviour of the errors in any way?

Yes, sorry I got distracted before I could add a comment about this.  I have 
indeed tested this and it does prevent the core files.

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Pablo Galindo Salgado]

Pablo Galindo Salgado  added the comment:

Apparently setting the env variable OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES 
should fix some fork-related changes. Have you tried already doing this? Does 
it change the behaviour of the errors in any way?

--
nosy: +pablogsal

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Barry A. Warsaw]

Barry A. Warsaw  added the comment:

That should of course be 10.14 Mojave.

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[issue35219] macOS 10.14 Mojave crashes in multiprocessing

[Barry A. Warsaw]

Change by Barry A. Warsaw :


--
title: macOS 10.14 High Sierra crashes in multiprocessing -> macOS 10.14 Mojave 
crashes in multiprocessing

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