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Relation between threads and signals unclear #58661
Description
| BPO | 14456 |
|---|---|
| Nosy | @pitrou, @vstinner, @smarnach |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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GitHub fields:
assignee = None
closed_at = <Date 2012-03-31.19:15:45.741>
created_at = <Date 2012-03-30.23:12:58.024>
labels = ['docs']
title = 'Relation between threads and signals unclear'
updated_at = <Date 2016-04-11.02:47:20.948>
user = 'https://github.com/smarnach'bugs.python.org fields:
activity = <Date 2016-04-11.02:47:20.948>
actor = 'python-dev'
assignee = 'docs@python'
closed = True
closed_date = <Date 2012-03-31.19:15:45.741>
closer = 'pitrou'
components = ['Documentation']
creation = <Date 2012-03-30.23:12:58.024>
creator = 'smarnach'
dependencies = []
files = []
hgrepos = []
issue_num = 14456
keywords = []
message_count = 7.0
messages = ['157156', '157158', '157160', '157222', '157223', '157238', '263160']
nosy_count = 6.0
nosy_names = ['pitrou', 'vstinner', 'neologix', 'docs@python', 'python-dev', 'smarnach']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue14456'
versions = ['Python 3.3']
Activity
smarnach commentedon Mar 30, 2012
The documentation of the 'signal' module states on the one hand
On the other hand, it provides the function 'pthread_kill()':
These two passages are in contradiction to each other. The documentation also states that only the main thread can set signal handlers -- if this is true, it is utterly unclear how sending signals to other threads is useful.
Probably the documentation wasn't fully updated when the above function was introduced.
smarnach commentedon Mar 30, 2012
For reference: the functions 'pthread_kill()' etc. were intrduced in bpo-8407.
vstinner commentedon Mar 30, 2012
By default, a thread signal can receive any signal and the signal handler implemented in C will be called in the context of the thread.
CPython ensures that a signal handler implemented in Python and installed by signal.signal() will be called in the main thread. It uses a signal handler implemented in C which only store the notification and will be the Python signal handler later (as early as possible).
pthread_sigmask() can be used to mask some signals (or all signals) on a specific thread.
python-dev commentedon Mar 31, 2012
New changeset 52e32f3b933d by Antoine Pitrou in branch '3.2':
Issue bpo-14456: improve documentation of the signal module w.r.t. threads.
http://hg.python.org/cpython/rev/52e32f3b933d
New changeset 44d13f371811 by Antoine Pitrou in branch 'default':
Issue bpo-14456: improve documentation of the signal module w.r.t. threads.
http://hg.python.org/cpython/rev/44d13f371811
pitrou commentedon Mar 31, 2012
Should be fixed now.
smarnach commentedon Mar 31, 2012
Thanks, Antoine! It's perfectly clear now, and the newly introduces headlines are a definite improvement.
python-dev commentedon Apr 11, 2016
New changeset 73050563053f by Martin Panter in branch '3.5':
Issue bpo-14456: Remove contradiction about blocking signals from bad merge
https://hg.python.org/cpython/rev/73050563053f
New changeset a8dbe6016a31 by Martin Panter in branch 'default':
Issue bpo-14456: Merge signal doc fix from 3.5
https://hg.python.org/cpython/rev/a8dbe6016a31