Maybe it's more the `a ||= b` that acts like a `a = a or b` in Python?
But then I don't think there is a confusion on Python side because
languages with a || operator usually already has a simple | with a
different meaning.
Le jeu. 27 févr. 2020 à 00:28, Nick Coghlan a écrit :
>
>
>
> On Thu., 27
On Thu., 27 Feb. 2020, 2:03 am Guido van Rossum, wrote:
> On Wed, Feb 26, 2020 at 7:43 AM Claudio Jolowicz
> wrote:
>
>> In my experience, the expression `value |= other` is a common idiom across
>> programming languages to provide a default for `value` if it is "unset".
>>
>
> Interesting. Can
https://discuss.python.org/t/3-7-7-schedule-accelerated-cutoff-now-2020-03-02/3511
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Done.
Thanks,
--Elad
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Hi Elad,
Can you open an issue on https://bugs.python.org/ and post your
findings there? I don't think it makes sense to continue discussing
this on python-dev.
(note that opening a bug doesn't mean it will be fixed quickly, but at
least it's recorded somewhere instead of being lost in the mai
I believe that the problem is in logging/__init__.py, which registers an
atfork() handler for re-initializing its lock. However, as part of this process
it attempts to acquire the module lock, which has not been reinitialized and so
still reflects the parent's state of the lock.
--Elad
Admittedly, the whole distutils spawn code should be rewritten to use
subprocess.
Regards
Antoine.
On Wed, 26 Feb 2020 17:52:53 -
"Elad Lahav" wrote:
> A change to posix_spawnp() fixes the problem for me:
>
> diff --git a/Lib/distutils/spawn.py b/Lib/distutils/spawn.py
> index c
A simple example that reproduces the hang (please keep in mind that I have very
little experience writing Python code...):
import os
from concurrent.futures import ThreadPoolExecutor
def new_process(arg):
pid = os.fork()
if pid == 0:
exec_fn("/bin/true
A change to posix_spawnp() fixes the problem for me:
diff --git a/Lib/distutils/spawn.py b/Lib/distutils/spawn.py
index ceb94945dc..cb69de4242 100644
--- a/Lib/distutils/spawn.py
+++ b/Lib/distutils/spawn.py
@@ -90,7 +90,7 @@ def _spawn_posix(cmd, search_path=1, verbose=0,
dry
It's actually not clear to me what lock it is from the core file I took, as
rlock_acquire() is called through a function pointer from
method_vectorcall_VARARGS_KEYWORDS() (I posted the backtrace separately).
My suspicion is that it doesn't fail on macOS because it may keep all of the
semaphore'
Sorry, should have posted the backtrace from the beginning. It goes deeper than
this, but the important part is in the child after fork():
#0 SyncSemWait () at
/builds/workspace/710-SDP/build_x86_64/lib/c/kercalls/x86_64/SyncSemWait.S:37
#1 0x004bfa174ac6 in PyThread_acquire_lock_timed
(l
Here's our current proposal for docs. Is there anything you'd like to add?
https://github.com/python/cpython/pull/18659/files
On Wed, Feb 26, 2020 at 8:12 AM David Mertz wrote:
> I think the "if unset" behavior is well handled by collections.ChainMap.
> But I do think that fact should be promine
Hi,
On Tue, 25 Feb 2020 11:48:44 -
e2la...@gmail.com wrote:
> Hello,
>
> I have successfully built Python 3.8.1 on QNX, but ran into a problem when
> using 'make -j4'. The build process invariably hangs with multiple
> single-threaded child processes stuck indefinitely waiting on semaphor
I think the "if unset" behavior is well handled by collections.ChainMap.
But I do think that fact should be prominent in any documentation of the
new dict Union operator.
On Wed, Feb 26, 2020, 11:06 AM Guido van Rossum wrote:
> On Wed, Feb 26, 2020 at 7:43 AM Claudio Jolowicz
> wrote:
>
>> In m
What semaphore is the subprocess blocking on? I.e. where in the Python code
(presumably of ThreadPoolExecutor) is that semaphore defined?
Given your hypothesis of the cause of the problem, can you perhaps write a
much simper program (which is simpler to debug and simpler to reason about)
that exhi
On Wed, Feb 26, 2020 at 7:43 AM Claudio Jolowicz
wrote:
> In my experience, the expression `value |= other` is a common idiom across
> programming languages to provide a default for `value` if it is "unset".
> For a
> container-type, I would expect this operation, informally spoken, to be
> appli
More information:
The hang happens when building extensions, using the setup.py script. The
script determines that the build is parallel (build_ext.py/build_extensions)
and creates a thread pool. Each thread then executes a compilation job by
fork()ing a compiler process.
I don't see how it wor
First off, apologies for entering the discussion after it has formally
ended.
I'm not sure this has any relevance now that the PEP is accepted and the
reference implementation merged. If not, sorry and feel free to ignore.
"Leftmost Value (First-Seen) Wins" was rejected because
> it is not clear
> I remember seeing it too. It may have originally been in the tracker
> instructions, but should definitely be in the devguide now.
>From looking through the devguide for every instance of "CLA" and
"trivial", there seems to be just one section that mentions anything
regarding the triviality of
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