[ https://issues.apache.org/jira/browse/SPARK-21985?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Stuart updated SPARK-21985: --------------------------- Description: PySpark fails to deserialize double-zipped RDDs. For example, the following example used to work in Spark 2.0.2: ``` >>> a = sc.parallelize('aaa') >>> b = sc.parallelize('bbb') >>> c = sc.parallelize('ccc') >>> a_bc = a.zip( b.zip(c) ) >>> a_bc.collect() [('a', ('b', 'c')), ('a', ('b', 'c')), ('a', ('b', 'c'))] ``` But in Spark >=2.1.0, it fails: {{ >>> a_bc.collect() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/magnetic/workspace/spark-2.2.0-bin-hadoop2.7/python/pyspark/rdd.py", line 810, in collect return list(_load_from_socket(port, self._jrdd_deserializer)) File "/magnetic/workspace/spark-2.2.0-bin-hadoop2.7/python/pyspark/serializers.py", line 329, in _load_stream_without_unbatching if len(key_batch) != len(val_batch): TypeError: object of type 'itertools.izip' has no len() }} As you can see, the error seems to be caused by [a check in the PairDeserializer class|https://github.com/apache/spark/blob/master/python/pyspark/serializers.py#L346-L348]: {{ if len(key_batch) != len(val_batch): raise ValueError("Can not deserialize PairRDD with different number of items" " in batches: (%d, %d)" % (len(key_batch), len(val_batch))) }} If that check is removed, then the example above works without error. Can the check simply be removed? was: PySpark fails to deserialize double-zipped RDDs. For example, the following example used to work in Spark 2.0.2: {{ >>> a = sc.parallelize('aaa') >>> b = sc.parallelize('bbb') >>> c = sc.parallelize('ccc') >>> a_bc = a.zip( b.zip(c) ) >>> a_bc.collect() [('a', ('b', 'c')), ('a', ('b', 'c')), ('a', ('b', 'c'))] }} But in Spark >=2.1.0, it fails: {{ >>> a_bc.collect() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/magnetic/workspace/spark-2.2.0-bin-hadoop2.7/python/pyspark/rdd.py", line 810, in collect return list(_load_from_socket(port, self._jrdd_deserializer)) File "/magnetic/workspace/spark-2.2.0-bin-hadoop2.7/python/pyspark/serializers.py", line 329, in _load_stream_without_unbatching if len(key_batch) != len(val_batch): TypeError: object of type 'itertools.izip' has no len() }} As you can see, the error seems to be caused by [a check in the PairDeserializer class|https://github.com/apache/spark/blob/master/python/pyspark/serializers.py#L346-L348]: {{ if len(key_batch) != len(val_batch): raise ValueError("Can not deserialize PairRDD with different number of items" " in batches: (%d, %d)" % (len(key_batch), len(val_batch))) }} If that check is removed, then the example above works without error. Can the check simply be removed? > PySpark PairDeserializer is broken for double-zipped RDDs > --------------------------------------------------------- > > Key: SPARK-21985 > URL: https://issues.apache.org/jira/browse/SPARK-21985 > Project: Spark > Issue Type: Bug > Components: PySpark > Affects Versions: 2.1.0, 2.1.1, 2.2.0 > Reporter: Stuart > Labels: bug > > PySpark fails to deserialize double-zipped RDDs. For example, the following > example used to work in Spark 2.0.2: > ``` > >>> a = sc.parallelize('aaa') > >>> b = sc.parallelize('bbb') > >>> c = sc.parallelize('ccc') > >>> a_bc = a.zip( b.zip(c) ) > >>> a_bc.collect() > [('a', ('b', 'c')), ('a', ('b', 'c')), ('a', ('b', 'c'))] > ``` > But in Spark >=2.1.0, it fails: > {{ > >>> a_bc.collect() > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > File "/magnetic/workspace/spark-2.2.0-bin-hadoop2.7/python/pyspark/rdd.py", > line 810, in collect > return list(_load_from_socket(port, self._jrdd_deserializer)) > File > "/magnetic/workspace/spark-2.2.0-bin-hadoop2.7/python/pyspark/serializers.py", > line 329, in _load_stream_without_unbatching > if len(key_batch) != len(val_batch): > TypeError: object of type 'itertools.izip' has no len() > }} > As you can see, the error seems to be caused by [a check in the > PairDeserializer > class|https://github.com/apache/spark/blob/master/python/pyspark/serializers.py#L346-L348]: > {{ > if len(key_batch) != len(val_batch): > raise ValueError("Can not deserialize PairRDD with different number of > items" > " in batches: (%d, %d)" % (len(key_batch), > len(val_batch))) > }} > If that check is removed, then the example above works without error. Can > the check simply be removed? -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org