在Apache Beam中使用Spark的StateSpec,可以通过以下步骤实现:
from pyspark.streaming import StreamingContext
from pyspark.streaming.kafka import KafkaUtils
from apache_beam.runners import spark
from apache_beam.transforms.trigger import AccumulationMode
from apache_beam.transforms.window import FixedWindows
from apache_beam.transforms.trigger import AfterWatermark, AfterProcessingTime
from apache_beam.transforms.trigger import AfterCount, Repeatedly
from apache_beam.runners.interactive import interactive_beam as ib
ssc = StreamingContext(spark.sparkContext, batchDuration=1)
kafkaParams = {"metadata.broker.list": "localhost:9092"}
topics = {"test": 1}
dstream = KafkaUtils.createStream(ssc, kafkaParams, topics, storageLevel="MEMORY_AND_DISK")
beam.StreamingContext
包装Spark Streaming上下文:p = beam.Pipeline(runner=ib.InteractiveRunner(), options=PipelineOptions())
pssc = beam.StreamingContext(stream_context=ssc, pipeline=p)
# 使用StateSpec定义状态
state_spec = beam.transforms.trigger.TimerSpec(
accumulation_mode=AccumulationMode.DISCARDING,
trigger=Repeatedly(
AfterCount(2),
AfterProcessingTime(10)
),
watermark=AfterWatermark(5)
)
# 将输入DStream转换为PCollection
input_collection = pssc.apply_beam_transform(lambda x: x[1])
# 使用StateSpec作为参数传递给ParDo转换
output_collection = input_collection.apply_beam_transform_with_state(
lambda element, state: process_element_with_state(element, state),
state_spec
)
# 定义处理逻辑
def process_element_with_state(element, state):
# 处理逻辑
...
# 更新状态
state.add(element)
# 返回处理结果
return result
# 输出结果
output_collection.apply_beam_transform(lambda x: print(x))
ssc.start()
ssc.awaitTermination()
请注意,上述代码示例假设您已经配置好了Apache Beam和Spark,并且已经在Spark上运行了Kafka。您还需要根据您的实际情况进行适当的修改和调整。