Scrapy with selenium, webdriver failing to instantiate

问题

I am trying to use selenium/phantomjs with scrapy and I'm riddled with errors. For example, take the following code snippet:

def parse(self, resposne):

    while True:
        try:
            driver = webdriver.PhantomJS()
            # do some stuff
            driver.quit()
            break
        except (WebDriverException, TimeoutException):
            try:
                driver.quit()
            except UnboundLocalError:
                print "Driver failed to instantiate"
            time.sleep(3)
            continue

A lot of the times the driver it seems it has failed to instantiate (so the driver is unbound, hence the exception), and I get the blurb (along with the print message I put in)

Exception AttributeError: "'Service' object has no attribute 'process'" in <bound method Service.__del__ of <selenium.webdriver.phantomjs.service.Service object at 0x7fbb28dc17d0>> ignored

Googling around, it seems everyone suggests updating phantomjs, which I have (1.9.8 built from source). Would anyone know what else could be causing this problem and a suitable diagnosis?

回答1:

The reason for this behavior is how the PhantomJS driver's Service class is implemented.

There is a __del__ method defined that calls self.stop() method:

def __del__(self):
    # subprocess.Popen doesn't send signal on __del__;
    # we have to try to stop the launched process.
    self.stop()

And, self.stop() is assuming the service instance is still alive trying to access it's attributes:

def stop(self):
    """
    Cleans up the process
    """
    if self._log:
        self._log.close()
        self._log = None
    #If its dead dont worry
    if self.process is None:
        return

    ...

The same exact problem is perfectly described in this thread:

Python attributeError on __del__

What you should do is to silently ignore AttributeError occurring while quitting the driver instance:

try:
    driver.quit()
except AttributeError:
    pass

The problem was introduced by this revision. Which means that downgrading to 2.40.0 would also help.

回答2:

I had that problem because phantomjs was not available from script (was not in path). You can check it by running phantomjs in console.

回答3:

Selenium version 2.44.0 on pypi needs the following patch in Service.__init__ of selenium.webdriver.common.phantomjs.service

self.process = None

I was thinking of submitting a patch but this already exists in the most recent version on google code.

来源：https://stackoverflow.com/questions/27674088/scrapy-with-selenium-webdriver-failing-to-instantiate

标签

python

selenium

selenium-webdriver

scrapy

phantomjs