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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2016/01/15 15:11:39 UTC
[jira] [Commented] (SPARK-12834) Use type conversion instead of
Ser/De of Pickle to transform JavaArray and JavaList
[ https://issues.apache.org/jira/browse/SPARK-12834?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15101809#comment-15101809 ]
Apache Spark commented on SPARK-12834:
--------------------------------------
User 'yinxusen' has created a pull request for this issue:
https://github.com/apache/spark/pull/10772
> Use type conversion instead of Ser/De of Pickle to transform JavaArray and JavaList
> -----------------------------------------------------------------------------------
>
> Key: SPARK-12834
> URL: https://issues.apache.org/jira/browse/SPARK-12834
> Project: Spark
> Issue Type: Improvement
> Reporter: Xusen Yin
>
> According to the Ser/De code in Python side:
> {code:title=StringIndexerModel|theme=FadeToGrey|linenumbers=true|language=python|firstline=0001|collapse=false}
> def _java2py(sc, r, encoding="bytes"):
> if isinstance(r, JavaObject):
> clsName = r.getClass().getSimpleName()
> # convert RDD into JavaRDD
> if clsName != 'JavaRDD' and clsName.endswith("RDD"):
> r = r.toJavaRDD()
> clsName = 'JavaRDD'
> if clsName == 'JavaRDD':
> jrdd = sc._jvm.SerDe.javaToPython(r)
> return RDD(jrdd, sc)
> if clsName == 'DataFrame':
> return DataFrame(r, SQLContext.getOrCreate(sc))
> if clsName in _picklable_classes:
> r = sc._jvm.SerDe.dumps(r)
> elif isinstance(r, (JavaArray, JavaList)):
> try:
> r = sc._jvm.SerDe.dumps(r)
> except Py4JJavaError:
> pass # not pickable
> if isinstance(r, (bytearray, bytes)):
> r = PickleSerializer().loads(bytes(r), encoding=encoding)
> return r
> {code}
> We use SerDe.dumps to serialize JavaArray and JavaList in PythonMLLibAPI, then deserialize them with PickleSerializer in Python side. However, there is no need to transform them in such an inefficient way. Instead of it, we can use type conversion to convert them, e.g. list(JavaArray) or list(JavaList). What's more, there is an issue to Ser/De Scala Array as I said in https://issues.apache.org/jira/browse/SPARK-12780
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