'tb'在作業前提到

Question

我在我的項目中使用from multiprocessing.dummy import Pool。問題是，經過許多成功的嘗試（獲得價格）後，它返回UnboundLocalError: local variable 'tb' referenced before assignment。

事情是tb變量應該100％分配時，它被引用。如果發生異常，則分配tb，否則返回變量d並且不引用tb。

我不知道哪裏可能是問題。我會告訴你我的功能 - 你可以看到該變量tb，這是一個traceback，在所有情況下，被分配當其referrenced：

def scan_partner(d): 
    success = False 
    try: 
     from parser import parse_price 
     resp = get_price(d.get('url'), d.get('xpath')) 
     amount = resp.get('price') 

    except XPathEvalError as xee: 
     tb = traceback.format_exc() 
     ticket_code = 'xpath' 
     msg = u'XPath Error' 
    except (requests.Timeout, requests.ConnectTimeout, requests.ReadTimeout): 
     tb = traceback.format_exc() 
     ticket_code = 'timeout' 
     msg = u'Timeout' 
    except requests.HTTPError: 
     tb = traceback.format_exc() 
     ticket_code = 'http' 
     msg = u'HTTP Error' 
    except decimal.DecimalException: 
     tb = traceback.format_exc() 
     ticket_code = 'decimal' 
     msg = u'Decimal Error' 
    except requests.ConnectionError: 
     tb = traceback.format_exc() 
     ticket_code = 'connection' 
     msg = u'Connection Error' 
    except Exception as e: 
     tb = traceback.format_exc() 
     ticket_code = 'unknown' 
     msg = u'Unknown Error' 
    else: 
     success = True 
     result = {'result': {'success': True, 
          'amount': str(amount)}} 
     d.update(result) 

    finally: 
     if success: 
      return d 
     d.update({'ticket': {'tb': tb, 
          'msg': msg, 
          'ticket_code': ticket_code}, 
        'result': {'success': False}}) 
     return d 


def scan_partners_dummy_pool(dicts_list): 
    repeated_results = [] 

    results_to_repeat = [] 
    for i in range(settings.ENGINE_NUMBER_OF_SCAN_REPEATS): 
     pool = Pool(300) 
     results = pool.map(scan_partner, dicts_list) 
     pool.close() 
     pool.join() 
     results_to_go = [] 
     results_to_repeat = [] 
     for result in results: 
      if result['result']['success']: 
       results_to_go.append(result) 
      else: 
       if result['ticket']['ticket_code']=='timeout': 
        results_to_repeat.append(result) 
       else: 
        results_to_go.append(result) 
     repeated_results.extend(results_to_go) 
     dicts_list = results_to_repeat 
    repeated_results.extend(results_to_repeat) 

    return repeated_results 

回溯：

[2017-02-11 23:33:54,470: ERROR/MainProcess] Task engineapp.tasks.scan_every_20_minutes[91c08f5d-36ad-42bc-805f-8a35c01127e6] raised unexpected: UnboundLocalError("local variable 'tb' referenced before assignment",) 
Traceback (most recent call last): 
    File "c:\users\milano\pycharmprojects\dropboxworkspaces\priceist_workspace\priceist_venv\lib\site-packages\celery\app\trace.py", line 240, in trace_task 
    R = retval = fun(*args, **kwargs) 
    File "c:\users\milano\pycharmprojects\dropboxworkspaces\priceist_workspace\priceist_venv\lib\site-packages\celery\app\trace.py", line 438, in __protected_call__ 
    return self.run(*args, **kwargs) 
    File "C:\Users\Milano\Desktop\Projekty\FS Dropbox\Dropbox\priceist\engineapp\tasks.py", line 18, in scan_every_20_minutes 
    scan_all_active_users(20) 
    File "c:\users\milano\pycharmprojects\dropboxworkspaces\priceist_workspace\priceist_venv\lib\site-packages\celery\local.py", line 167, in <lambda> 
    __call__ = lambda x, *a, **kw: x._get_current_object()(*a, **kw) 
    File "c:\users\milano\pycharmprojects\dropboxworkspaces\priceist_workspace\priceist_venv\lib\site-packages\celery\app\trace.py", line 439, in __protected_call__ 
    return orig(self, *args, **kwargs) 
    File "c:\users\milano\pycharmprojects\dropboxworkspaces\priceist_workspace\priceist_venv\lib\site-packages\celery\app\task.py", line 420, in __call__ 
    return self.run(*args, **kwargs) 
    File "C:\Users\Milano\Desktop\Projekty\FS Dropbox\Dropbox\priceist\engineapp\tasks.py", line 132, in scan_all_active_users 
    report = scan_user(user.id, simple_schedule) 
    File "C:\Users\Milano\Desktop\Projekty\FS Dropbox\Dropbox\priceist\engineapp\tasks.py", line 123, in scan_user 
    results = scan_partners_dummy_pool(partners_dicts) 
    File "C:\Users\Milano\Desktop\Projekty\FS Dropbox\Dropbox\priceist\engineapp\engine\scraper.py", line 126, in scan_partners_dummy_pool 
    if result['ticket']['ticket_code']=='timeout': 
    File "c:\python27\Lib\multiprocessing\pool.py", line 251, in map 
    return self.map_async(func, iterable, chunksize).get() 
    File "c:\python27\Lib\multiprocessing\pool.py", line 567, in get 
    raise self._value 
UnboundLocalError: local variable 'tb' referenced before assignment 

PS： 該過程是一個Celery定期任務。

Answer 1

您還沒有捕獲所有可能的異常，所以如果你的例外是不是Exception則既不except塊也不else塊將執行子類，但finally塊將被下執行。

我會將return陳述放入else中，並將finally區塊的內容移到主體。那麼你可能會看到什麼BaseException造成麻煩。