我有一个长期运行的Python服务器,希望能够在不重新启动服务器的情况下升级服务。最好的方法是什么?
if foo.py has changed:
unimport foo <-- How do I do this?
import foo
myfoo = foo.Foo()
我有一个长期运行的Python服务器,希望能够在不重新启动服务器的情况下升级服务。最好的方法是什么?
if foo.py has changed:
unimport foo <-- How do I do this?
import foo
myfoo = foo.Foo()
当前回答
这是重新加载一个模块的现代方式:
from importlib import reload
如果你想支持3.5以上的Python版本,请使用以下命令:
from sys import version_info
if version_info[0] < 3:
pass # Python 2 has built in reload
elif version_info[0] == 3 and version_info[1] <= 4:
from imp import reload # Python 3.0 - 3.4
else:
from importlib import reload # Python 3.5+
这定义了一个重载方法,可以通过模块调用来重载它。例如,reload(math)将重载数学模块。
其他回答
Python不会在重载时重新计算子模块地址,如果它在sys.modules中
这里有一个变通办法,虽然不完美,但有效。
# Created by BaiJiFeiLong@gmail.com at 2022/2/19 18:50
import importlib
import types
import urllib.parse
import urllib.request
def reloadModuleWithChildren(mod):
mod = importlib.reload(mod)
for k, v in mod.__dict__.items():
if isinstance(v, types.ModuleType):
setattr(mod, k, importlib.import_module(v.__name__))
fakeParse = types.ModuleType("urllib.parse")
realParse = urllib.parse
urllib.parse = fakeParse
assert urllib.parse is fakeParse
importlib.reload(urllib)
assert urllib.parse is fakeParse
assert getattr(urllib, "parse") is fakeParse
reloadModuleWithChildren(urllib)
assert urllib.parse is not fakeParse
assert urllib.parse is realParse
对于Python 2,使用内置函数reload:
reload(module)
对于Python 2和Python 3.2-3.3,使用reload from module imp:
import imp
imp.reload(module)
对于Python≥3.4,imp已弃用,改用importlib,因此使用以下命令:
import importlib
importlib.reload(module)
or:
from importlib import reload
reload(module)
TL; diana:
Python≥3.4:importlib.reload(module) Python 3.2 - 3.3: imp.reload(module) Python 2: reload(module)
编辑(答案V2)
前面的解决方案只适用于获取重置信息,但它不会更改所有引用(超过重新加载,但小于所需)。为了设置所有的引用,我必须进入垃圾收集器,并在那里重写引用。现在它就像一个咒语!
请注意,如果GC被关闭,或者如果重新加载不受GC监视的数据,这将不起作用。如果您不想打乱GC,原始答案可能就足够了。
新代码:
import importlib
import inspect
import gc
from enum import EnumMeta
from weakref import ref
_readonly_attrs = {'__annotations__', '__call__', '__class__', '__closure__', '__code__', '__defaults__', '__delattr__',
'__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__func__', '__ge__', '__get__',
'__getattribute__', '__globals__', '__gt__', '__hash__', '__init__', '__init_subclass__',
'__kwdefaults__', '__le__', '__lt__', '__module__', '__name__', '__ne__', '__new__', '__qualname__',
'__reduce__', '__reduce_ex__', '__repr__', '__self__', '__setattr__', '__sizeof__', '__str__',
'__subclasshook__', '__weakref__', '__members__', '__mro__', '__itemsize__', '__isabstractmethod__',
'__basicsize__', '__base__'}
def reset_module(module, inner_modules_also=True):
"""
This function is a stronger form of importlib's `reload` function. What it does, is that aside from reloading a
module, it goes to the old instance of the module, and sets all the (not read-only) attributes, functions and classes
to be the reloaded-module's
:param module: The module to reload (module reference, not the name)
:param inner_modules_also: Whether to treat ths module as a package as well, and reload all the modules within it.
"""
# For the case when the module is actually a package
if inner_modules_also:
submods = {submod for _, submod in inspect.getmembers(module)
if (type(submod).__name__ == 'module') and (submod.__package__.startswith(module.__name__))}
for submod in submods:
reset_module(submod, True)
# First, log all the references before reloading (because some references may be changed by the reload operation).
module_tree = _get_tree_references_to_reset_recursively(module, module.__name__)
new_module = importlib.reload(module)
_reset_item_recursively(module, module_tree, new_module)
def _update_referrers(item, new_item):
refs = gc.get_referrers(item)
weak_ref_item = ref(item)
for coll in refs:
if type(coll) == dict:
enumerator = coll.keys()
elif type(coll) == list:
enumerator = range(len(coll))
else:
continue
for key in enumerator:
if weak_ref_item() is None:
# No refs are left in the GC
return
if coll[key] is weak_ref_item():
coll[key] = new_item
def _get_tree_references_to_reset_recursively(item, module_name, grayed_out_item_ids = None):
if grayed_out_item_ids is None:
grayed_out_item_ids = set()
item_tree = dict()
attr_names = set(dir(item)) - _readonly_attrs
for sub_item_name in attr_names:
sub_item = getattr(item, sub_item_name)
item_tree[sub_item_name] = [sub_item, None]
try:
# Will work for classes and functions defined in that module.
mod_name = sub_item.__module__
except AttributeError:
mod_name = None
# If this item was defined within this module, deep-reset
if (mod_name is None) or (mod_name != module_name) or (id(sub_item) in grayed_out_item_ids) \
or isinstance(sub_item, EnumMeta):
continue
grayed_out_item_ids.add(id(sub_item))
item_tree[sub_item_name][1] = \
_get_tree_references_to_reset_recursively(sub_item, module_name, grayed_out_item_ids)
return item_tree
def _reset_item_recursively(item, item_subtree, new_item):
# Set children first so we don't lose the current references.
if item_subtree is not None:
for sub_item_name, (sub_item, sub_item_tree) in item_subtree.items():
try:
new_sub_item = getattr(new_item, sub_item_name)
except AttributeError:
# The item doesn't exist in the reloaded module. Ignore.
continue
try:
# Set the item
_reset_item_recursively(sub_item, sub_item_tree, new_sub_item)
except Exception as ex:
pass
_update_referrers(item, new_item)
原来的答案
正如在@bobince的回答中所写的,如果在另一个模块中已经有对该模块的引用(特别是如果它是用As关键字导入的,如import numpy As np),该实例将不会被覆盖。
当应用需要配置模块的“全新”状态的测试时,这对我来说是相当有问题的,所以我写了一个名为reset_module的函数,它使用importlib的reload函数并递归地覆盖所有声明的模块属性。它已经用Python版本3.6进行了测试。
import importlib
import inspect
from enum import EnumMeta
_readonly_attrs = {'__annotations__', '__call__', '__class__', '__closure__', '__code__', '__defaults__', '__delattr__',
'__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__func__', '__ge__', '__get__',
'__getattribute__', '__globals__', '__gt__', '__hash__', '__init__', '__init_subclass__',
'__kwdefaults__', '__le__', '__lt__', '__module__', '__name__', '__ne__', '__new__', '__qualname__',
'__reduce__', '__reduce_ex__', '__repr__', '__self__', '__setattr__', '__sizeof__', '__str__',
'__subclasshook__', '__weakref__', '__members__', '__mro__', '__itemsize__', '__isabstractmethod__',
'__basicsize__', '__base__'}
def reset_module(module, inner_modules_also=True):
"""
This function is a stronger form of importlib's `reload` function. What it does, is that aside from reloading a
module, it goes to the old instance of the module, and sets all the (not read-only) attributes, functions and classes
to be the reloaded-module's
:param module: The module to reload (module reference, not the name)
:param inner_modules_also: Whether to treat ths module as a package as well, and reload all the modules within it.
"""
new_module = importlib.reload(module)
reset_items = set()
# For the case when the module is actually a package
if inner_modules_also:
submods = {submod for _, submod in inspect.getmembers(module)
if (type(submod).__name__ == 'module') and (submod.__package__.startswith(module.__name__))}
for submod in submods:
reset_module(submod, True)
_reset_item_recursively(module, new_module, module.__name__, reset_items)
def _reset_item_recursively(item, new_item, module_name, reset_items=None):
if reset_items is None:
reset_items = set()
attr_names = set(dir(item)) - _readonly_attrs
for sitem_name in attr_names:
sitem = getattr(item, sitem_name)
new_sitem = getattr(new_item, sitem_name)
try:
# Set the item
setattr(item, sitem_name, new_sitem)
try:
# Will work for classes and functions defined in that module.
mod_name = sitem.__module__
except AttributeError:
mod_name = None
# If this item was defined within this module, deep-reset
if (mod_name is None) or (mod_name != module_name) or (id(sitem) in reset_items) \
or isinstance(sitem, EnumMeta): # Deal with enums
continue
reset_items.add(id(sitem))
_reset_item_recursively(sitem, new_sitem, module_name, reset_items)
except Exception as ex:
raise Exception(sitem_name) from ex
注意事项:请谨慎使用!在非外围模块(例如,定义外部使用的类的模块)上使用这些可能会导致Python中的内部问题(例如pickle / unpickling问题)。
下面的代码允许你兼容Python 2/3:
try:
reload
except NameError:
# Python 3
from imp import reload
你可以在两个版本中使用它作为reload(),这让事情变得更简单。
Enthought Traits有一个模块很好地解决了这个问题。https://traits.readthedocs.org/en/4.3.0/_modules/traits/util/refresh.html
它将重新加载任何已更改的模块,并更新正在使用它的其他模块和实例对象。它在__very_private__方法的大多数时候都不起作用,并且可能会阻塞类继承,但它为我节省了大量的时间,使我不必在编写PyQt gui或在Maya或Nuke等程序中运行的东西时重新启动主机应用程序。它可能有20% - 30%的时间不起作用,但它仍然非常有帮助。
Enthought的包不会在文件更改时重新加载它们——您必须显式地调用它——但如果您确实需要它,实现它应该不是那么困难