Apache Spark 无法查看输出

Question

我刚刚开始学习 Apache Spark。我正在尝试打印链接的输出，但由于某种原因它没有显示。我也试过 links.collect() ， display(links) 但其中 none 有效。任何帮助将不胜感激。

第二张图片的完整堆栈跟踪：

 Py4JJavaError                             Traceback (most recent call last)
  <ipython-input-34-01e857cfa45e> in <module>()
  ----> 1 for link in links.collect():
        2         print("%s" %(link))

  /databricks/spark/python/pyspark/rdd.py in collect(self)
      769         """
      770         with SCCallSiteSync(self.context) as css:
  --> 771             port = self.ctx._jvm.PythonRDD.collectAndServe(self._jrdd.rdd())
      772         return list(_load_from_socket(port, self._jrdd_deserializer))
      773 

  /databricks/spark/python/lib/py4j-0.9-src.zip/py4j/java_gateway.py in __call__(self, *args)
      811         answer = self.gateway_client.send_command(command)
      812         return_value = get_return_value(
  --> 813             answer, self.gateway_client, self.target_id, self.name)
      814 
      815         for temp_arg in temp_args:

  /databricks/spark/python/pyspark/sql/utils.py in deco(*a, **kw)
       43     def deco(*a, **kw):
       44         try:
  ---> 45             return f(*a, **kw)
       46         except py4j.protocol.Py4JJavaError as e:
       47             s = e.java_exception.toString()

  /databricks/spark/python/lib/py4j-0.9-src.zip/py4j/protocol.py in get_return_value(answer, gateway_client, target_id, name)
      306                 raise Py4JJavaError(
      307                     "An error occurred while calling {0}{1}{2}.\n".
  --> 308                     format(target_id, ".", name), value)
      309             else:
      310                 raise Py4JError(

  Py4JJavaError: An error occurred while calling z:org.apache.spark.api.python.PythonRDD.collectAndServe.
  : org.apache.spark.SparkException: Job aborted due to stage failure: Task 4 in stage 24.0 failed 1 times, most recent failure: Lost task 4.0 in stage 24.0 (TID 76, localhost): org.apache.spark.api.python.PythonException: Traceback (most recent call last):
    File "/databricks/spark/python/pyspark/worker.py", line 111, in main
      process()
    File "/databricks/spark/python/pyspark/worker.py", line 106, in process
      serializer.dump_stream(func(split_index, iterator), outfile)
    File "/databricks/spark/python/pyspark/rdd.py", line 2346, in pipeline_func
      return func(split, prev_func(split, iterator))
    File "/databricks/spark/python/pyspark/rdd.py", line 2346, in pipeline_func
      return func(split, prev_func(split, iterator))
    File "/databricks/spark/python/pyspark/rdd.py", line 317, in func
      return f(iterator)
    File "/databricks/spark/python/pyspark/rdd.py", line 1776, in combineLocally
      merger.mergeValues(iterator)
    File "/databricks/spark/python/pyspark/shuffle.py", line 236, in mergeValues
      for k, v in iterator:
    File "<ipython-input-31-4b09041aa30b>", line 1, in <lambda>
    File "<ipython-input-28-f43debc22073>", line 3, in parseNeighbors
    File "/databricks/python/lib/python2.7/re.py", line 171, in split
      return _compile(pattern, flags).split(string, maxsplit)
  TypeError: expected string or buffer

    at org.apache.spark.api.python.PythonRunner$$anon.read(PythonRDD.scala:166)
    at org.apache.spark.api.python.PythonRunner$$anon.<init>(PythonRDD.scala:207)
    at org.apache.spark.api.python.PythonRunner.compute(PythonRDD.scala:125)
    at org.apache.spark.api.python.PythonRDD.compute(PythonRDD.scala:70)
    at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:306)
    at org.apache.spark.rdd.RDD.iterator(RDD.scala:270)
    at org.apache.spark.api.python.PairwiseRDD.compute(PythonRDD.scala:342)
    at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:306)
    at org.apache.spark.rdd.RDD.iterator(RDD.scala:270)
    at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:79)
    at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:46)
    at org.apache.spark.scheduler.Task.run(Task.scala:96)
    at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:222)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

Answer 1

你的映射函数错误错误类似于

re.split(r'\s+',[('a b')])

尝试将其替换为

parts=re.split(r'\s+',urls[0])

这将发送

re.split(r'\s+',('a b'))

整行都发送到您的地图函数，因此您需要通过调用它们来访问单元格，例如 .map(lambda row: (row[0], row[1])

Apache Spark 无法查看输出

Apache Spark Not able to view output

apache-spark

pyspark

databricks