Walter Bogorad created SPARK-3992:
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Summary: Spark 1.1.0 python binding cannot use any collections but
list as Accumulators
Key: SPARK-3992
URL: https://issues.apache.org/jira/browse/SPARK-3992
Project: Spark
Issue Type: Bug
Components: PySpark
Affects Versions: 1.1.0
Environment: 3.13.0-36-generic #63-Ubuntu SMP Wed Sep 3 21:30:07 UTC
2014 x86_64 x86_64 x86_64 GNU/Linux
Reporter: Walter Bogorad
A dictionary accumulator defined as a global variable is not visible inside a
function called by "foreach()".
Here is the minimal code snippet:
from collections import defaultdict
from pyspark import SparkContext
from pyspark.accumulators import AccumulatorParam
class DictAccumParam(AccumulatorParam):
def zero(self, value):
value.clear()
def addInPlace(self, val1, val2):
return val1
sc = SparkContext("local", "Dict Accumulator Bug")
va = sc.accumulator(defaultdict(int), DictAccumParam())
def foo(x):
global va
print "va is:", va
rdd = sc.parallelize([1,2,3]).foreach(foo)
When ran the code snippet produced the following results:
...
va is: None
va is: None
va is: None
...
I have verified that the global variables are visible inside foo() called by
foreach only if they are for scalars or lists like in the API doc at
http://spark.apache.org/docs/latest/api/python/
The problem exists with standard dictionaries and collections.
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