出现错误“ImportError：找不到“input_readers”在路径“映射缩减”上尝试启动mapReduce作业

Question

尝试通过 http://localhost:8080/mapreduce 启动器页面。

看来我的问题与这篇文章类似，AppEngine 映射器 API 导入错误。不幸的是，没有给出明确的答案。

我将其简化为这个小 testmapreduce.py:

from google.appengine.ext import db

class TestEntity(db.Model):
    value = db.StringProperty()

def mapperhandler(test):
    print test.value
    return

和我的 mapreduce.yaml:

mapreduce:
- name: Simplest MapReduce
  mapper:
    handler: testmapreduce.mapperhandler
    input_reader: mapreduce.input_readers.DatastoreInputReader
    params:
    - name: entity_kind
      default: testmapreduce.TestEntity

一个可能的线索是 __init__.py 的存在没有效果（无论是在项目根目录、mapreduce 目录还是两者中）。我确信我犯了一个初学者错误，但在过去的几天里，我阅读了所有文档以及我能找到的所有示例。谢谢。

更新： 我尝试通过...调用它时遇到相同的错误

control.start_map(
   "Give awards",
   "testmapreduce.mapperhandler",
   "mapreduce.input_readers.DatastoreInputReader",
   {"entity_kind": "testmapreduce.TestEntity"},
   shard_count=10)

更新： 根据要求，堆栈跟踪 - 让我知道还有什么会有帮助......

ERROR    2011-10-16 17:09:27,216 _webapp25.py:464] Could not find 'input_readers' on path 'mapreduce'
Traceback (most recent call last):
 File "/Develop/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/google/appengine/ext/webapp/_webapp25.py", line 701, in __call__
   handler.get(*groups)
 File "/Users/lc/PycharmProjects/mrtest/testmapreduce.py", line 22, in get
   shard_count=10)      # handle web form test interface
 File "/Users/lc/PycharmProjects/mrtest/mapreduce/control.py", line 94, in start_map
   transactional=transactional)
 File "/Users/lc/PycharmProjects/mrtest/mapreduce/handlers.py", line 811, in _start_map
   mapper_input_reader_class = mapper_spec.input_reader_class()
 File "/Users/lc/PycharmProjects/mrtest/mapreduce/model.py", line 393, in input_reader_class
   return util.for_name(self.input_reader_spec)
 File "/Users/lc/PycharmProjects/mrtest/mapreduce/util.py", line 94, in for_name
   module = for_name(module_name, recursive=True)
 File "/Users/lc/PycharmProjects/mrtest/mapreduce/util.py", line 102, in for_name
   short_name, module_name))
ImportError: Could not find 'input_readers' on path 'mapreduce'
INFO     2011-10-16 22:09:27,253 dev_appserver.py:4247] "GET /giveawards HTTP/1.1" 500 -

Answer 1

这个问题原来是因为我在本地环境中使用了2.7版本的Python Interpreter。当我切换到2.5时，它工作得很好。