Question

我正在尝试构建一个简单的管道，使用Kafka作为Spark的结构化流API的流源，执行分组聚合并将结果保存到HDFS。

但是，一旦我提交作业，即使流量数据的数量非常少，我也会收到Java堆空间错误。

以下是pyspark中的代码：

allEvents =spark \
    .readStream \
    .format("kafka") \
    .option("kafka.bootstrap.servers", "localhost:9092") \
    .option("subscribe","MyNewTopic") \
    .option("group.id","aggStream") \
    .option("startingOffsets", "earliest") \
    .load() \
    .select(col("value").cast("string"))

aaIDF = allEvents.filter(col("value").contains("myNewAPI")).select(from_json(col("value"),aaISchema) \
 .alias("colName")).select(col("colName.eventTime"), col("colName.appId"),col("colName.articleId"),col("colName.locale"),col("colName.impression"))

windowedCountsDF = aaIDF.withWatermark("eventTime","10 minutes") \
    .groupBy("appId","articleId","locale",window("eventTime", "2 minutes")).sum("impression").withColumnRenamed("sum(impression)", "views")


query = windowedCountsDF \
    .writeStream \
    .outputMode("append") \
    .format("parquet") \
    .option("path", "/CDS/events/JS/agg/" + strftime("%Y/%m/%d/%H/%M", gmtime()) + "/") \
    .option("checkpointLocation", "/CDS/checkpoint/").start()

以下是例外情况：

17/11/23 14:24:45 ERROR Utils: Aborting task
java.lang.OutOfMemoryError: Java heap space
    at org.apache.spark.sql.catalyst.expressions.codegen.BufferHolder.grow(BufferHolder.java:73)
    at org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter.write(UnsafeRowWriter.java:214)
    at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.agg_doAggregateWithKeys$(Unknown Source)
    at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.processNext(Unknown Source)
    at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
    at org.apache.spark.sql.execution.WholeStageCodegenExec$$anonfun$8$$anon$1.hasNext(WholeStageCodegenExec.scala:395)
    at org.apache.spark.sql.execution.datasources.FileFormatWriter$SingleDirectoryWriteTask.execute(FileFormatWriter.scala:315)
    at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$org$apache$spark$sql$execution$datasources$FileFormatWriter$$executeTask$3.apply(FileFormatWriter.scala:258)
    at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$org$apache$spark$sql$execution$datasources$FileFormatWriter$$executeTask$3.apply(FileFormatWriter.scala:256)
    at org.apache.spark.util.Utils$.tryWithSafeFinallyAndFailureCallbacks(Utils.scala:1375)
    at org.apache.spark.sql.execution.datasources.FileFormatWriter$.org$apache$spark$sql$execution$datasources$FileFormatWriter$$executeTask(FileFormatWriter.scala:261)
    at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$write$1$$anonfun$apply$mcV$sp$1.apply(FileFormatWriter.scala:191)
    at org.apache.spark.sql.execution.datasources.FileFormatWriter$$anonfun$write$1$$anonfun$apply$mcV$sp$1.apply(FileFormatWriter.scala:190)
    at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
    at org.apache.spark.scheduler.Task.run(Task.scala:108)
    at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:335)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:748)

Answer 1

两个可能的原因：

您的水印设置无法生效。您应该使用colName.eventTime引用该列。

由于未定义水印（仅在其他类别中定义），因此不会丢弃旧的聚合状态。
您应该为Spark设置更大的值--driver-memory或--executor-memory。

Answer 2

您需要在提交作业时拥有适当的驱动程序并执行内存集。这个post简要介绍了如何设置这些配置。

Spark Structured Streaming立即抛出Java OOM

2 个答案: