单例Selenium ChromeDriver随机连接失败，求故障原因

问题现象 #

运行特定测试集时，约50%概率出现连接超时错误，错误触发在调用driver.get(website_url)时，其他30个使用相同配置的测试均正常运行。

报错信息 #

tests\certificate\test_mysoftware_Netwrk_ClientGroup.py:56: in setup_method
    delete_testClients()
lib\mysoftware_ClientGroup.py:195: in delete_testClients
    driver.get(website_url)
venv\lib\site-packages\selenium\webdriver\remote\webdriver.py:363: in get
    self.execute(Command.GET, {"url": url})
venv\lib\site-packages\selenium\webdriver\remote\webdriver.py:354: in execute
    self.error_handler.check_response(response)
venv\lib\site-packages\selenium\webdriver\remote\errorhandler.py:229: in check_response
    raise exception_class(message, screen, stacktrace)
E   selenium.common.exceptions.WebDriverException: Message: unknown error: net::ERR_CONNECTION_TIMED_OUT
E     (Session info: chrome=128.0.6613.114)
E   Stacktrace:
E       GetHandleVerifier [0x00007FF72A7BB652+29090]
E       (No symbol) [0x00007FF72A72E709]
E       (No symbol) [0x00007FF72A5EB1CA]
E       (No symbol) [0x00007FF72A5E3204]
E       (No symbol) [0x00007FF72A5D4179]
E       (No symbol) [0x00007FF72A5D5F42]
E       (No symbol) [0x00007FF72A5D443F]
E       (No symbol) [0x00007FF72A5D3CD1]
E       (No symbol) [0x00007FF72A5D3C10]
E       (No symbol) [0x00007FF72A5D1AD3]
E       (No symbol) [0x00007FF72A5D214C]
E       (No symbol) [0x00007FF72A5EE231]
E       (No symbol) [0x00007FF72A6873FE]
E       (No symbol) [0x00007FF72A6666EA]
E       (No symbol) [0x00007FF72A6865D9]
E       (No symbol) [0x00007FF72A666493]
E       (No symbol) [0x00007FF72A6309B1]
E       (No symbol) [0x00007FF72A631B11]
E       GetHandleVerifier [0x00007FF72AAD8CDD+3295277]
E       GetHandleVerifier [0x00007FF72AB248C3+3605523]
E       GetHandleVerifier [0x00007FF72AB1A787+3564247]
E       GetHandleVerifier [0x00007FF72A876F36+797318]
E       (No symbol) [0x00007FF72A73988F]
E       (No symbol) [0x00007FF72A735474]
E       (No symbol) [0x00007FF72A735600]
E       (No symbol) [0x00007FF72A724A9F]
E       BaseThreadInitThunk [0x00007FFB1DDD7374+20]
E       RtlUserThreadStart [0x00007FFB1FADCC91+33]

环境信息 #

• 系统：Windows 10
• Python版本：3.10
• Selenium版本：4.18.1
• Chrome与ChromeDriver版本：统一为128.0.6613.114

Driver配置代码 #

def get_driver_options():
    options = webdriver.ChromeOptions()
    options.add_argument("--headless=new")
    options.add_argument("--window-size=1440, 900")
    options.add_argument('--ignore-certificate-errors')
    options.add_argument('--allow-running-insecure-content')
    options.add_argument("--disable-extensions")
    options.add_argument("--proxy-server='direct://'")
    options.add_argument("--proxy-bypass-list=*")
    options.add_argument("--start-maximized")
    options.add_argument('--disable-gpu')
    options.add_argument('--disable-dev-shm-usage')
    options.add_argument("--FontRenderHinting[none]")
    options.add_argument('--no-sandbox')
    options.add_argument('log-level=3')
    options.add_argument('--ignore-ssl-errors=yes')
    options.add_argument('--allow-insecure-localhost')
    options.add_argument('--remote-allow-origins=*')
    options.add_argument('--disable-search-engine-choice-screen')
    return options

单例WebDriver实现代码 #

class SdriverMeta(type):
    _instances =  {}
    _lock: Lock = Lock()

    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            try:
                instance = super().__call__(*args, **kwargs)
                cls._instances[cls] = instance
            except Exception as e:
                if cls in cls._instances:
                    del cls._instances[cls]
                raise
        return cls._instances[cls]

    @classmethod
    def get_lock(cls):
        return cls._lock

    @classmethod
    def reset_instance(cls):
        with cls._lock:
            if cls in cls._instances:
                del cls._instances[cls]

class SDriver(metaclass=SdriverMeta):
    _instance = None
    def __new__(cls,headless = True):
        if not hasattr(cls, "_instance") or cls._instance is None:
            with cls._lock:
                cls._instance = super(SDriver, cls).__new__(cls)
                cls._instance.headless = headless
                cls._instance.driver = None
        return cls._instance

    def get_driver(self,headless = True):
        with SdriverMeta.get_lock():
            if self.driver is None:
                if headless:
                    options = get_driver_options()
                else:
                    options = get_driver_headfull_options()
                service = Service()
                self.driver = webdriver.Chrome(service=service, options=options) 
                self.driver.implicitly_wait(90)
        return self.driver

    def close_driver(self):
        with SdriverMeta.get_lock():
            if hasattr(self, "driver") and self.driver:
                try:
                    self.driver.close()
                    self.driver.quit()
                except Exception as e:
                    print(f"Failed to close the driver: {e}")
                finally:
                    self.driver = None
        SdriverMeta.reset_instance()

触发错误的代码段 #

def delete_testClients():
        sdriver = SDriver()
        headless=True
        driver = sdriver.get_driver(headless)
        website_url = default_config["website_url"]
        driver.get(website_url)

已排查内容 #

• 确认Chrome与ChromeDriver版本完全匹配，排除版本不兼容问题
• 验证目标URL正确无误
• 同配置的其他30个测试无异常，排除Driver配置本身问题

怀疑方向 #

推测问题可能与单例Driver的生命周期管理有关，但暂未定位具体原因，需进一步排查。

内容的提问来源于stack exchange，提问作者ajax