Python Problems - Revision history

Roman V M at 19:44, 1 September 2022

2022-09-01T19:44:30Z

← Older revision		Revision as of 19:44, 1 September 2022
Line 6:		Line 6:
	There is an old [[Python debugging\|Python bug]]<ref name="bug_27400" /> which ''only'' impacts embedded Python applications, such as the Kodi Python environment. The issue is that <code>datetime.strptime</code><ref name="pydocs_datetime" /> is only initialized once per process, and not every time the embedded environment is reinitialized. This causes <code>datetime.strptime</code> to return <code>None</code> (and perhaps other strange behavior).		There is an old [[Python debugging\|Python bug]]<ref name="bug_27400" /> which ''only'' impacts embedded Python applications, such as the Kodi Python environment. The issue is that <code>datetime.strptime</code><ref name="pydocs_datetime" /> is only initialized once per process, and not every time the embedded environment is reinitialized. This causes <code>datetime.strptime</code> to return <code>None</code> (and perhaps other strange behavior).

	=== ~~Resolution options~~ ===		=== Workaround ===
	One option is for you to replace every reference to <code>datetime.strptime</code> to use a [[#Patch\|patch]], the code of which is shown below on this page. This involves less voodoo, but there is always the possibility that some library code uses <code>strptime</code> and that will cause the potential for incorrect results or a full Kodi crash, e.g. the [[Add-on:Youtube-dl\|YouTube-dl]] add-on (<kbd>script.module.youtube.dl</kbd>) was crashing Kodi for a while.		The workaround is to monkey-patch <code>datetime.strptime</code> so that any user of the Python runtime will use it. It is more voodoo-like, but situations like this are why Python ''natively supports'' [[wikipedia:Monkey patch\|monkey patching]], after all. The typically excellent Python documentation manages to be both thorough and concise simultaneously with regards to <code>datetime.strptime</code> and is well worth reviewing before deciding which angle of attack best suits your use case.<ref name="pydocs_strptime" />; it discusses some of the differences between <code>datetime.strptime</code> and <code>time.strptime</code>.<ref name="pydocs_differences" />

	The ~~other option~~ is to monkey-patch <code>datetime.strptime</code> so that any user of the Python runtime will use it. It is more voodoo-like, but situations like this are why Python ''natively supports'' [[wikipedia:Monkey patch\|monkey patching]], after all. The typically excellent Python documentation manages to be both thorough and concise simultaneously with regards to <code>datetime.strptime</code> and is well worth reviewing before deciding which angle of attack best suits your use case.<ref name="pydocs_strptime" />; it discusses some of the differences between <code>datetime.strptime</code> and <code>time.strptime</code>.<ref name="pydocs_differences" />

	=== Patch ===		=== Patch ===
	This patch simply replaces <code>datetime.strptime</code> with <code>time.strptime</code> as they are nearly identical in function. The original Kodi-specific implementation and its commit history are available on GitHub as part of <code>script.module.kutils</code>.<ref name="kutils_source" /> Essentially, the patch is:		This patch simply replaces <code>datetime.strptime</code> with <code>time.strptime</code> as they are nearly identical in function. The original Kodi-specific implementation and its commit history are available on GitHub as part of <code>script.module.kutils</code>.<ref name="kutils_source" /> Essentially, the patch is:
	<syntaxhighlight lang="python">		<syntaxhighlight lang="python">
	~~@staticmethod~~		import datetime
	~~def monkey_patch_strptime():~~		import time
	~~# Check if problem exists (don't want to stomp on patch applied earlier)~~
	~~try:~~
	datetime.datetime~~.strptime('0', '%H'~~)		class proxydt(datetime.datetime):
	~~except TypeError~~:
	~~# Globally replace Python's datetime.datetime.strptime with~~		@classmethod
	~~# the version here.~~		def strptime(cls, date_string, format):
	~~datetime.datetime = StripTimePatch.strptime~~		return datetime.datetime(*(time.strptime(date_string, format)[:6]))
	@~~staticmethod~~
	def strptime(date_string~~: str~~, ~~date_format: str~~) ~~-> datetime.datetime~~:
	~~result: datetime.datetime~~		datetime.datetime = proxydt
	~~result =~~ datetime.datetime(*(time.strptime(date_string, ~~date_format~~)[0:6]))
	~~return result~~
	</syntaxhighlight>		</syntaxhighlight>

			== asyncio ==

			It is a known [https://github.com/python/cpython/issues/91375 issue] that <code>asyncio</code> module or rather its C-based implementation does not support embedded Python environments that use sub-interpreters, such as Kodi Python environment. Essentially it means that only one addon can start the event loop by calling <code>asyncio.run()</code> and others will fail with <code>RuntimeError</code>.

			=== Workaround ===

			The workaround is to disable C-based <code>asyncio</code> module and use its pure-Python implementation. This can be done by the following code that should be put at the beginning of your addon entrypoint script:
			<syntaxhighlight lang="python">
			import sys
			sys.modules['_asyncio'] = None
			</syntaxhighlight>

			You will loose possible performance benefits of <code>asyncio</code> but your async Python code won't fail.

	== References ==		== References ==

RogueScholar: Fix dead end page status with wikilinks and inline citations, and also −Category:Development; +Category:Python using HotCat

2022-08-29T13:26:13Z

Fix dead end page status with wikilinks and inline citations, and also −Category:Development; +Category:Python using HotCat

← Older revision		Revision as of 13:26, 29 August 2022
Line 1:		Line 1:
			{{Mininav\|[[Development]]\|[[Add-on development]]\|[[About Add-ons]]}}<br />

	This page is meant to document Python issues of general interest to Kodi addon developers.		This page is meant to document Python issues of general interest to Kodi addon developers.

	== datetime.strptime ==		== datetime.strptime ==
	There is an old Python bug ~~(https://bugs.python.org~~/~~issue27400)~~ which ~~ONLY~~ impacts embedded ~~python~~ applications, such as the Kodi Python environment. The issue is that datetime.strptime is only initialized once per process and not every time the embedded environment is reinitialized. This causes datetime.strptime to return None and perhaps other strange behavior.		There is an old [[Python debugging\|Python bug]]<ref name="bug_27400" /> which ''only'' impacts embedded Python applications, such as the Kodi Python environment. The issue is that <code>datetime.strptime</code><ref name="pydocs_datetime" /> is only initialized once per process, and not every time the embedded environment is reinitialized. This causes <code>datetime.strptime</code> to return <code>None</code> (and perhaps other strange behavior).

	One option is for you to replace every reference to datetime.strptime to use a ~~strptime_patch attached to~~ this page. This is less voodoo, but there is always the possibility that some library code uses strptime and ~~there~~ will ~~still be~~ potential for incorrect results or a Kodi crash (script.module.youtube.dl ~~crashed~~ Kodi for a while).		=== Resolution options ===
			One option is for you to replace every reference to <code>datetime.strptime</code> to use a [[#Patch\|patch]], the code of which is shown below on this page. This involves less voodoo, but there is always the possibility that some library code uses <code>strptime</code> and that will cause the potential for incorrect results or a full Kodi crash, e.g. the [[Add-on:Youtube-dl\|YouTube-dl]] add-on (<kbd>script.module.youtube.dl</kbd>) was crashing Kodi for a while.

	The other option is to monkey-patch datetime.strptime so that any user of the ~~python~~ runtime will use it. It is voodoo like, but ~~that is~~ why Python supports Monkey patching. ~~See~~ Python documentation on datetime.strptime ~~(https:~~/~~/docs~~.~~python.org~~/~~3/library/datetime.html#strftime-strptime-behavior). It~~ discusses some of the differences between datetime.strptime and time.strptime.		The other option is to monkey-patch <code>datetime.strptime</code> so that any user of the Python runtime will use it. It is more voodoo-like, but situations like this are why Python ''natively supports'' [[wikipedia:Monkey patch\|monkey patching]], after all. The typically excellent Python documentation manages to be both thorough and concise simultaneously with regards to <code>datetime.strptime</code> and is well worth reviewing before deciding which angle of attack best suits your use case.<ref name="pydocs_strptime" />; it discusses some of the differences between <code>datetime.strptime</code> and <code>time.strptime</code>.<ref name="pydocs_differences" />

	This patch simply replaces datetime.strptime with time.strptime~~. They~~ are nearly identical in function. ~~For more information, see: https://github.com/fbacher/~~script.module.kutils/~~blob/master/lib/kutils~~/~~strptime_patch.py.~~ Essentially the patch is:		=== Patch ===
			This patch simply replaces <code>datetime.strptime</code> with <code>time.strptime</code> as they are nearly identical in function. The original Kodi-specific implementation and its commit history are available on GitHub as part of <code>script.module.kutils</code>.<ref name="kutils_source" /> Essentially, the patch is:
	@staticmethod		<syntaxhighlight lang="python">
			@staticmethod
	def monkey_patch_strptime():		def monkey_patch_strptime():
	# Check if problem exists (don't want to stomp on patch applied earlier)		# Check if problem exists (don't want to stomp on patch applied earlier)
Line 23:		Line 28:
	result = datetime.datetime(*(time.strptime(date_string, date_format)[0:6]))		result = datetime.datetime(*(time.strptime(date_string, date_format)[0:6]))
	return result		return result
			</syntaxhighlight>

			== References ==
			<div class="plainlinks"><references>
			<ref name="bug_27400">Weinberg, Denny ({{#Dateformat:2016-06-27\|mdy}}). [https://github.com/python/cpython/issues/71587 '''Issue #71587: Datetime NoneType after calling Py_Finalize and Py_Initialize''']. [https://github.com/python/cpython/issues ''Python Issue Tracker''] on [https://github.com/ GitHub].</ref>
			<ref name="pydocs_datetime">[https://docs.python.org/3/ <span style="text-decoration: underline;">Python 3 Documentation</span>] ({{#dateformat:2022-08-28\|mdy}}). [https://docs.python.org/3/library/index.html The Python Standard Library] » [https://docs.python.org/3/library/datatypes.html Data Types] » [https://docs.python.org/3/library/datetime.html#module-datetime datetime — Basic date and time types] ― <span style="font-weight: 600;">[https://docs.python.org/3/library/datetime.html#datetime.datetime.strptime ''classmethod'' <kbd>datetime.'''strptime'''(''date_string, format'')</kbd>]</span> ― from the source code found in [https://github.com/python/cpython/blob/main/Lib/datetime.py Lib/datetime.py].</ref>
			<ref name="pydocs_strptime">[https://docs.python.org/3/ <span style="text-decoration: underline;">Python 3 Documentation</span>] ({{#dateformat:2022-08-28\|mdy}}). datetime — Basic date and time types » <span style="font-weight: 600;">[https://docs.python.org/3/library/datetime.html#strftime-and-strptime-behavior <kbd>strftime()</kbd> and <kbd>strptime()</kbd> Behavior]</span>.</ref>
			<ref name="pydocs_differences">[https://docs.python.org/3/ <span style="text-decoration: underline;">Python 3 Documentation</span>] ({{#dateformat:2022-08-28\|mdy}}). <kbd>strftime()</kbd> and <kbd>strptime()</kbd> Behavior » <span style="font-weight: 600;">[https://docs.python.org/3.10/library/datetime.html#technical-detail Technical Detail]</span>.</ref>
			<ref name="kutils_source"><span style="font-weight: 600;">[https://github.com/fbacher/script.module.kutils/blob/master/lib/kutils/strptime_patch.py <kbd>lib/kutils/strptime_patch.py</kbd>]</span> ({{#dateformat:2022-01-11\|mdy}}) in <code>script.module.kutils</code>, ''"A helper module for Kodi development"'' on GitHub.</ref>
			</references></div>


	[[Category:~~Development~~]]		[[Category:Python]]

RogueScholar: added Category:Development using HotCat

2022-03-19T21:05:18Z

added Category:Development using HotCat

← Older revision		Revision as of 21:05, 19 March 2022
Line 23:		Line 23:
	result = datetime.datetime(*(time.strptime(date_string, date_format)[0:6]))		result = datetime.datetime(*(time.strptime(date_string, date_format)[0:6]))
	return result		return result

			[[Category:Development]]

Fbacher at 18:18, 11 January 2022

2022-01-11T18:18:29Z

← Older revision		Revision as of 18:18, 11 January 2022
Line 9:		Line 9:
	This patch simply replaces datetime.strptime with time.strptime. They are nearly identical in function. For more information, see: https://github.com/fbacher/script.module.kutils/blob/master/lib/kutils/strptime_patch.py. Essentially the patch is:		This patch simply replaces datetime.strptime with time.strptime. They are nearly identical in function. For more information, see: https://github.com/fbacher/script.module.kutils/blob/master/lib/kutils/strptime_patch.py. Essentially the patch is:

	~~<nowiki>~~ @staticmethod		@staticmethod
	def monkey_patch_strptime():		def monkey_patch_strptime():
	# Check if problem exists (don't want to stomp on patch applied earlier)		# Check if problem exists (don't want to stomp on patch applied earlier)
Line 17:		Line 17:
	# Globally replace Python's datetime.datetime.strptime with		# Globally replace Python's datetime.datetime.strptime with
	# the version here.		# the version here.

	datetime.datetime = StripTimePatch.strptime		datetime.datetime = StripTimePatch.strptime
			@staticmethod
	@staticmethod
	def strptime(date_string: str, date_format: str) -> datetime.datetime:		def strptime(date_string: str, date_format: str) -> datetime.datetime:
	result: datetime.datetime		result: datetime.datetime
	result = datetime.datetime(*(time.strptime(date_string, date_format)[0:6]))		result = datetime.datetime(*(time.strptime(date_string, date_format)[0:6]))
	return result		return result
	~~</nowiki>~~

Fbacher at 18:14, 11 January 2022

2022-01-11T18:14:58Z

@@ Line 5: / Line 5: @@
 One option is for you to replace every reference to datetime.strptime to use a strptime_patch attached to this page. This is less voodoo, but there is always the possibility that some library code uses strptime and there will still be potential for incorrect results or a Kodi crash (script.module.youtube.dl crashed Kodi for a while).
-The other option is to monkey-patch datetime.strptime so that any user of the python runtime will use it. It is voodoo like, but that is why Python supports Monkey patching.
+The other option is to monkey-patch datetime.strptime so that any user of the python runtime will use it. It is voodoo like, but that is why Python supports Monkey patching. See Python documentation on datetime.strptime (https://docs.python.org/3/library/datetime.html#strftime-strptime-behavior). It discusses some of the differences between datetime.strptime and time.strptime.
-This patch simply replaces datetime.strptime with time.strptime. They are nearly identical in function. For more information, see the attached patch.
+This patch simply replaces datetime.strptime with time.strptime. They are nearly identical in function. For more information, see: https://github.com/fbacher/script.module.kutils/blob/master/lib/kutils/strptime_patch.py. Essentially the patch is:

Fbacher: Created page with "This page is meant to document Python issues of general interest to Kodi addon developers. == datetime.strptime == There is an old Python bug (https://bugs.python.org/issue274..."

2022-01-11T15:22:41Z

Created page with "This page is meant to document Python issues of general interest to Kodi addon developers. == datetime.strptime == There is an old Python bug (https://bugs.python.org/issue274..."

New page

This page is meant to document Python issues of general interest to Kodi addon developers.
== datetime.strptime ==
There is an old Python bug (https://bugs.python.org/issue27400) which ONLY impacts embedded python applications, such as the Kodi Python environment. The issue is that datetime.strptime is only initialized once per process and not every time the embedded environment is reinitialized. This causes datetime.strptime to return None and perhaps other strange behavior.

One option is for you to replace every reference to datetime.strptime to use a strptime_patch attached to this page. This is less voodoo, but there is always the possibility that some library code uses strptime and there will still be potential for incorrect results or a Kodi crash (script.module.youtube.dl crashed Kodi for a while).

The other option is to monkey-patch datetime.strptime so that any user of the python runtime will use it. It is voodoo like, but that is why Python supports Monkey patching.

This patch simply replaces datetime.strptime with time.strptime. They are nearly identical in function. For more information, see the attached patch.