将 PCollection 分配回全局 window

Question

我有一个管道，它接受一个有界的 PCollection，为其分配时间戳，然后 "windows" 将其放入 Sliding Windows。分组转换后，我想将生成的 PCollection 分配回全局 window。我一直无法弄清楚如何做到这一点。请参阅下面的示例光束伪代码：

import apache_beam as beam

with beam.Pipeline() as p:
    (
        p
        | beam.io.ReadFromText()
        | beam.ParDo(AddTimestampDoFn())
        | beam.WindowInto(beam.window.SlidingWindows(60, 60))
        | beam.GroupByKey()
        | beam.ParDo(SomethingElse()
        | beam.WindowInto(GlobalWindow()) # Here is where I want to bring back to global window
    )

关于如何进行的任何想法？

Answer 1

使用 beam.WindowInto(window.GlobalWindows()) 应该可以。例如，通过这个快速测试：

data = [{'message': 'Hi', 'timestamp': time.time()}]

events = (p
  | 'Create Events' >> beam.Create(data) \
  | 'Add Timestamps' >> beam.Map(lambda x: beam.window.TimestampedValue(x, x['timestamp'])) \
  | 'Sliding Windows'   >> beam.WindowInto(beam.window.SlidingWindows(60, 60)) \
  | 'First window' >> beam.ParDo(DebugPrinterFn()) \
  | 'global Window'   >> beam.WindowInto(window.GlobalWindows()) \
  | 'Second window'   >> beam.ParDo(DebugPrinterFn()))

其中 DebugPrinterFn 打印 window 信息：

class DebugPrinterFn(beam.DoFn):
  """Just prints the element and window"""
  def process(self, element, window=beam.DoFn.WindowParam):
    logging.info("Received message %s in window=%s", element['message'], window)
    yield element

我得到以下输出：

INFO:root:Received message Hi in window=[1575565500.0, 1575565560.0)
INFO:root:Received message Hi in window=GlobalWindow

已使用 DirectRunner 和 2.16.0 SDK 进行测试。如果它不适合你：

你有任何错误吗？
您使用的是哪个运行器和 SDK？

完整代码here

将 PCollection 分配回全局 window

Assign PCollection back to global window

python

google-cloud-dataflow

apache-flink

apache-beam