无法在 Dataflow 中查看 beam.combiners.Count.PerElement() 的输出

Question

我有一个 Pub/Sub 脚本发布男性名字如下：

from google.cloud import pubsub_v1
import names

project_id = "Your-Project-Name"
topic_name = "Your-Topic-Name"

publisher = pubsub_v1.PublisherClient()
topic_path = publisher.topic_path(project_id, topic_name)

while True:
    data = names.get_first_name(gender='male') #u"Message number {}".format(n)
    data = data.encode("utf-8")
    publisher.publish(topic_path, data=data)

然后我有一个数据流，它从附加到主题的订阅中读取，然后按如下方式计算管道的每个元素：

import logging,re,os
import apache_beam as beam
from apache_beam.options.pipeline_options import  PipelineOptions

root = logging.getLogger()
root.setLevel(logging.INFO)

p = beam.Pipeline(options=PipelineOptions())
x = (
 p
 | beam.io.ReadFromPubSub(topic=None, subscription="projects/YOUR-PROJECT-NAME/subscriptions/YOUR-SUBSCRIPTION-NAME").with_output_types(bytes)
 | 'Decode_UTF-8' >> beam.Map(lambda x: x.decode('utf-8'))
 | 'ExtractWords' >> beam.FlatMap(lambda x: re.findall(r'[A-Za-z\']+', x))
 | 'CountingElem' >> beam.combiners.Count.PerElement()
 | 'FormatOutput' >> beam.MapTuple(lambda word, count: '%s: %s' % (word, count))
 | 'Printing2Log' >> beam.Map(lambda k: logging.info(k)))

result = p.run()
result.wait_until_finish()

问题是：我没有从管道的最后 3 个步骤获得任何输出，而我可以看到从管道的前 3 个步骤流出的数据 - 这意味着没有任何记录。

我期望这样的输出：

Peter: 2
Glen: 1
Alex: 1
Ryan: 2

我已经感谢你帮助我了

Answer 1

鉴于这是一个流式管道，您需要适当地设置 windowing/triggering 管道才能正常工作。见下文。 https://beam.apache.org/documentation/programming-guide/#windowing

更具体地说：

Caution: Beam’s default windowing behavior is to assign all elements of a PCollection to a single, global window and discard late data, even for unbounded PCollections. Before you use a grouping transform such as GroupByKey on an unbounded PCollection, you must do at least one of the following:

beam.combiners.Count.PerElement() 中包含一个 GroupByKey。

无法在 Dataflow 中查看 beam.combiners.Count.PerElement() 的输出

Unable to view output for beam.combiners.Count.PerElement() in Dataflow

google-cloud-platform

google-cloud-dataflow

apache-beam