我正在尝试编写一条管道，该管道定期检查Google存储桶中是否有新的.gz文件，这些文件实际上是压缩的.csv文件。然后，将这些记录写入BigQuery表。在添加.watchForNewFiles(...)和.withMethod(STREAMING_INSERTS)部分之前，以下代码在批处理模式下工作。我希望它能够以这些更改以流模式运行。但是我遇到了一个例外，就是我在网上找不到任何相关内容。这是我的代码：
public static void main(String[] args) {
DataflowDfpOptions options = PipelineOptionsFactory.fromArgs(args)
//.withValidation()
.as(DataflowDfpOptions.class);
Pipeline pipeline = Pipeline.create(options);
Stopwatch sw = Stopwatch.createStarted();
log.info("DFP data transfer from GS to BQ has started.");
pipeline.apply("ReadFromStorage", TextIO.read()
.from("gs://my-bucket/my-folder/*.gz")
.withCompression(Compression.GZIP)
.watchForNewFiles(
// Check for new files every 30 seconds
Duration.standardSeconds(30),
// Never stop checking for new files
Watch.Growth.never()
)
)
.apply("TransformToTableRow", ParDo.of(new TableRowConverterFn()))
.apply("WriteToBigQuery", BigQueryIO.writeTableRows()
.to(options.getTableId())
.withMethod(STREAMING_INSERTS)
.withCreateDisposition(CREATE_NEVER)
.withWriteDisposition(WRITE_APPEND)
.withSchema(TableSchema)); //todo: use withJsonScheme(String json) method instead
pipeline.run().waitUntilFinish();
log.info("DFP data transfer from GS to BQ is finished in {} seconds.", sw.elapsed(TimeUnit.SECONDS));
}
/**
* Creates a TableRow from a CSV line
*/
private static class TableRowConverterFn extends DoFn<String, TableRow> {
@ProcessElement
public void processElement(ProcessContext c) throws Exception {
String[] split = c.element().split(",");
//Ignore the header line
//Since this is going to be run in parallel, we can't guarantee that the first line passed to this method will be the header
if (split[0].equals("Time")) {
log.info("Skipped header");
return;
}
TableRow row = new TableRow();
for (int i = 0; i < split.length; i++) {
TableFieldSchema col = TableSchema.getFields().get(i);
//String is the most common type, putting it in the first if clause for a little bit optimization.
if (col.getType().equals("STRING")) {
row.set(col.getName(), split[i]);
} else if (col.getType().equals("INTEGER")) {
row.set(col.getName(), Long.valueOf(split[i]));
} else if (col.getType().equals("BOOLEAN")) {
row.set(col.getName(), Boolean.valueOf(split[i]));
} else if (col.getType().equals("FLOAT")) {
row.set(col.getName(), Float.valueOf(split[i]));
} else {
//Simply try to write it as a String if
//todo: Consider other BQ data types.
row.set(col.getName(), split[i]);
}
}
c.output(row);
}
}
以及堆栈跟踪：
java.lang.IllegalArgumentException: Not expecting a splittable ParDoSingle: should have been overridden
at org.apache.beam.repackaged.beam_runners_google_cloud_dataflow_java.com.google.common.base.Preconditions.checkArgument(Preconditions.java:122)
at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator.payloadForParDoSingle(PrimitiveParDoSingleFactory.java:167)
at org.apache.beam.runners.dataflow.PrimitiveParDoSingleFactory$PayloadTranslator.translate(PrimitiveParDoSingleFactory.java:145)
at org.apache.beam.runners.core.construction.PTransformTranslation.toProto(PTransformTranslation.java:206)
at org.apache.beam.runners.core.construction.SdkComponents.registerPTransform(SdkComponents.java:86)
at org.apache.beam.runners.core.construction.PipelineTranslation$1.visitPrimitiveTransform(PipelineTranslation.java:87)
at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit(TransformHierarchy.java:668)
at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit(TransformHierarchy.java:660)
at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit(TransformHierarchy.java:660)
at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit(TransformHierarchy.java:660)
at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit(TransformHierarchy.java:660)
at org.apache.beam.sdk.runners.TransformHierarchy$Node.visit(TransformHierarchy.java:660)
at org.apache.beam.sdk.runners.TransformHierarchy$Node.access$600(TransformHierarchy.java:311)
at org.apache.beam.sdk.runners.TransformHierarchy.visit(TransformHierarchy.java:245)
at org.apache.beam.sdk.Pipeline.traverseTopologically(Pipeline.java:458)
at org.apache.beam.runners.core.construction.PipelineTranslation.toProto(PipelineTranslation.java:59)
at org.apache.beam.runners.dataflow.DataflowPipelineTranslator.translate(DataflowPipelineTranslator.java:165)
at org.apache.beam.runners.dataflow.DataflowRunner.run(DataflowRunner.java:684)
at org.apache.beam.runners.dataflow.DataflowRunner.run(DataflowRunner.java:173)
at org.apache.beam.sdk.Pipeline.run(Pipeline.java:311)
at org.apache.beam.sdk.Pipeline.run(Pipeline.java:297)
at com.diply.data.App.main(App.java:66)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:282)
at java.lang.Thread.run(Thread.java:748)
这是我的命令，用于在Dataflow上发布作业：
clean compile exec:java -Dexec.mainClass=com.my.project.App "-Dexec.args=--runner=DataflowRunner --tempLocation=gs://my-bucket/tmp --tableId=Temp.TestTable --project=my-project --jobName=dataflow-dfp-streaming" -Pdataflow-runner
我使用的是Apache梁版本2.5.0。这是我的pom.xml中的相关部分。
<properties>
<beam.version>2.5.0</beam.version>
<bigquery.version>v2-rev374-1.23.0</bigquery.version>
<google-clients.version>1.23.0</google-clients.version>
...
</properties>
答案 0 :(得分：2)
使用Dataflow 2.4.0运行代码会给出一个更明确的错误：java.lang.UnsupportedOperationException: DataflowRunner does not currently support splittable DoFn
但是，this answer建议从2.2.0开始支持该功能。确实是这种情况，在this remark 之后，您需要在--streaming中添加Dexec.args选项以强制其进入流模式。
我用the code I supplied in the comments和your pom都用mine进行了测试，并且都在没有--streaming的情况下产生了错误2.在--streaming的情况下运行良好
您可能要打开一个github beam问题，因为据我所知，官方没有在任何地方对此行为进行记录。