Question

我正在寻找一种解决方案，可以在不等待答案的情况下发出大量异步网络请求。

这是我目前的代码：

import mechanize
from mechanize._opener import urlopen
from mechanize._form import ParseResponse
from multiprocessing import Pool

brow = mechanize.Browser()
brow.open('https://website.com')

#Login
brow.select_form(nr = 0)

brow.form['username'] = 'user'
brow.form['password'] = 'password'
brow.submit()

while(true):
    #async open the browser until some state is fullfilled
    brow.open('https://website.com/needthiswebsite')

上面代码的问题是，如果我尝试使两个浏览器开放，则bro2必须等待bro1完成才能启动。（阻止）

bro1.open('https://website.com/needthiswebsite')
bro2.open('https://website.com/needthiswebsite')

尝试解决方案：

#PSUDO-CODE

#GLOBAL VARIABLE STATE
boolean state = true

while(state):
    #async open the browser until some state is full filled
    #I spam this function until I get a positive answer from one of the calls
    pool = Pool(processes = 1)
    result = pool.apply_async(openWebsite,[brow1],callback = updateState)

def openWebsite(browser):
   result = browser.open('https://website.com/needthiswebsite')
   if result.something() == WHATIWANT:
        return true
   return false

def updateState(state):
    state = true

我试图为我的问题实现类似的解决方案，例如：有关stackoverflow的Asynchronous method call in Python?问题。

这个问题是我在尝试使用pool.apply_async（brow.open（））时遇到错误

错误味精：

PicklingError：无法腌制：属性查找内置 .function失败

我尝试过很多东西来尝试修复PicklingError但似乎没什么用。

是否可以使用mechanize做到这一点？
我应该更换为urllib2之类的其他库吗？

任何帮助都会非常感激：）

Answer 1

mechanize.Browser对象不是pickleable，因此无法传递给pool.apply_async（或任何其他需要将对象发送到子进程的方法）：

>>> b = mechanize.Browser()
>>> import pickle
>>> pickle.dumps(b)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/pickle.py", line 1374, in dumps
    Pickler(file, protocol).dump(obj)
  File "/usr/lib/python2.7/pickle.py", line 224, in dump
    self.save(obj)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 725, in save_inst
    save(stuff)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "/usr/lib/python2.7/pickle.py", line 663, in _batch_setitems
    save(v)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 600, in save_list
    self._batch_appends(iter(obj))
  File "/usr/lib/python2.7/pickle.py", line 615, in _batch_appends
    save(x)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 725, in save_inst
    save(stuff)
  File "/usr/lib/python2.7/pickle.py", line 286, in save
    f(self, obj) # Call unbound method with explicit self
  File "/usr/lib/python2.7/pickle.py", line 649, in save_dict
    self._batch_setitems(obj.iteritems())
  File "/usr/lib/python2.7/pickle.py", line 663, in _batch_setitems
    save(v)
  File "/usr/lib/python2.7/pickle.py", line 306, in save
    rv = reduce(self.proto)
  File "/usr/lib/python2.7/copy_reg.py", line 70, in _reduce_ex
    raise TypeError, "can't pickle %s objects" % base.__name__
TypeError: can't pickle instancemethod objects

最简单的方法是在每个子流程中创建Browser实例，而不是在父流中创建：

def openWebsite(url):
    brow = mechanize.Browser()
    brow.open('https://website.com')

    #Login
    brow.select_form(nr=0)

    brow.form['username'] = 'user'
    brow.form['password'] = 'password'
    brow.submit()

    result = brow.open(url)
    if result.something() == WHATIWANT:
         return True
    return False

理想情况下，您只能使用父进程中的Browser对象登录，然后在多个进程中发出并行请求，但可能需要花费大量精力才能生成对象pickleable（如果可能的话） - 即使你设法删除导致当前错误的instancemethod对象，除了Browser之外，{{1}}内还可能有更多不可解决的对象。

机械化+异步浏览器调用

1 个答案: