Question

所以，情况如下：
我使用GAE Pipeline lib作为流程，我的类FanoutPipeline来自库中的Pipeline类：

from pipeline import pipeline
class FanoutPipeline(pipeline.Pipeline):

当管道进程运行时，它会检查以验证该对象实际上是从Pipeline派生的类的实例，但它返回False：

  yielded = pipeline_iter.send(next_value)
  # here I check that yielded is an object of `FanoutPipeline`
  # class, plz see logs output below
  if isinstance(yielded, Pipeline):  # returns false here

我添加了大量日志来获取类树及其模块：

  import inspect
  logging.debug('Yielded: {}'.format(yielded))
  for cls in inspect.getmro(yielded.__class__):
      logging.debug('Yielded base: {}'.format(inspect.getmodule(cls)))
      logging.debug('Yielded base: {}'.format(cls))
  logging.debug('PipelineMeta classes: {}'.format(_PipelineMeta._all_classes))
  logging.debug('Pipeline: {}'.format(Pipeline))
  logging.debug('Pipeline module: {}'.format(inspect.getmodule(Pipeline)))
  for cls in inspect.getmro(Pipeline):
    logging.debug(inspect.getmodule(cls))
  if isinstance(yielded, Pipeline):

得到了输出：

D 21:55:48.079 Yielded: project.handlers.pipeline_gcm.FanoutPipeline(*(None, {u'campaign_id': u'xxx', u'campaign_name': u'xmas notification', u'execution': {u'action': u'market', u'conditions': {u'delayBetweenNotificationsHours': 0, u'in... (515 bytes), **{})
D 21:55:48.079 Yielded base: <module 'project.handlers.pipeline_gcm' from '/base/data/home/apps/s~project-dev3/9.389913797024223872/projects/handlers/pipeline_gcm.pyc'>
D 21:55:48.079 Yielded base: <class 'project.handlers.pipeline_gcm.FanoutPipeline'>
D 21:55:48.080 Yielded base: <module 'pipeline.pipeline' from '/base/data/home/apps/s~project-dev3/9.389913797024223872/libraries/pipeline/pipeline.pyc'>
D 21:55:48.080 Yielded base: <class 'pipeline.pipeline.Pipeline'>
D 21:55:48.080 Yielded base: <module '__builtin__' (built-in)>
D 21:55:48.080 Yielded base: <type 'object'>
D 21:55:48.081 PipelineMeta classes: [<class 'libraries.pipeline.pipeline.Pipeline'>]
D 21:55:48.081 Pipeline: <class 'libraries.pipeline.pipeline.Pipeline'>
D 21:55:48.081 Pipeline module: <module 'libraries.pipeline.pipeline' from '/base/data/home/apps/s~project-dev3/9.389913797024223872/libraries/pipeline/pipeline.pyc'>
D 21:55:48.082 <module 'libraries.pipeline.pipeline' from '/base/data/home/apps/s~project-dev3/9.389913797024223872/libraries/pipeline/pipeline.pyc'>
D 21:55:48.082 <module '__builtin__' (built-in)>

如您所见，在基类中已经明确pipeline.pipeline.Pipeline，模块路径匹配。

以下是一些可能发生的想法： 1.对象以某种方式在进程之间传递，并且检查失败，因为一个基类在一个进程中加载，另一个基类在另一个进程中加载。 2.相对路径存在差异，即创建对象的过程中的pipeline.pipeline模块和libraries.pipeline.pipeline在其使用过程中进行isinstance检查。

你能帮我解决一下这个问题吗？我应该首先尝试什么？这可能是造成这种失败的原因吗？

Answer 1

您正在导入该类的两个版本，一个版本为libraries.pipeline.pipeline.Pipeline，另一个版本为pipeline.pipeline.Pipeline。这意味着您在/base/data/home/apps/s~project-dev3/9.389913797024223872/中同时拥有/base/data/home/apps/s~project-dev3/9.389913797024223872/libraries和sys.path。虽然你知道它们只是通往同一模块的两条路径，但python并不知道这一点并将它们视为两个不同的类。

您需要决定是要将导入基于libraries还是libraries内的各种模块，然后一致地编写导入。你也应该停止添加＆＃34; unchosen＆＃34;目录到sys.path，以便以错误的方式导入模块，失败。

isinstance（）因未知原因返回False

1 个答案: