[jira] [Created] (SPARK-16262) Impossible to remake new SparkContext using SparkSession API in Pyspark

["Vladimir Feinberg (JIRA)" <ji...@apache.org>]

Vladimir Feinberg created SPARK-16262:
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             Summary: Impossible to remake new SparkContext using SparkSession API in Pyspark
                 Key: SPARK-16262
                 URL: https://issues.apache.org/jira/browse/SPARK-16262
             Project: Spark
          Issue Type: Bug
          Components: PySpark
            Reporter: Vladimir Feinberg


There are multiple use cases where one might like to be able to stop and re-start a {{SparkSession}}: configuration changes or modular testing. The following code demonstrates that without clearing a hidden global {{SparkSession._instantiatedContext = None}} it is impossible to re-create a new Spark session after stopping one in the same process:

{code}
>>> from pyspark.sql import SparkSession
>>> spark = SparkSession.builder.getOrCreate()
Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel).
16/06/28 11:28:10 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
16/06/28 11:28:10 WARN Utils: Your hostname, vlad-databricks resolves to a loopback address: 127.0.1.1; using 192.168.3.166 instead (on interface enp0s31f6)
16/06/28 11:28:10 WARN Utils: Set SPARK_LOCAL_IP if you need to bind to another address
>>> spark.stop()
>>> spark = SparkSession.builder.getOrCreate()
>>> spark.createDataFrame([(1,)])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "pyspark/sql/session.py", line 514, in createDataFrame
    rdd, schema = self._createFromLocal(map(prepare, data), schema)
  File "pyspark/sql/session.py", line 394, in _createFromLocal
    return self._sc.parallelize(data), schema
  File "pyspark/context.py", line 410, in parallelize
    numSlices = int(numSlices) if numSlices is not None else self.defaultParallelism
  File "pyspark/context.py", line 346, in defaultParallelism
    return self._jsc.sc().defaultParallelism()
AttributeError: 'NoneType' object has no attribute 'sc'
{code}



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