Hi,
I'm using spark 2.1.0 on AWS EMR (Yarn) and trying to use a UDF in python as
follows:
from pyspark.sql.functions import col, udf
from pyspark.sql.types import StringType
path = 's3://some/parquet/dir/myfile.parquet'
df = spark.read.load(path)
def _test_udf(useragent):
return useragent.upper()
test_udf = udf(_test_udf, StringType())
df = df.withColumn('test_field', test_udf(col('std_useragent')))
df.write.parquet('/output.parquet')
The following config is used in spark-defaults.conf (using
maximizeResourceAllocation in EMR)
...
spark.executor.instances 4
spark.executor.cores 8
spark.driver.memory 8G
spark.executor.memory 9658M
spark.default.parallelism 64
spark.driver.maxResultSize 3G
...
The cluster has 4 worker nodes (+1 master) with the following specs: 8 vCPU,
15 GiB memory, 160 SSD GB storage
The above example fails every single time with errors like the following:
17/09/06 09:58:08 WARN TaskSetManager: Lost task 26.1 in stage 1.0 (TID 50,
ip-172-31-7-125.eu-west-1.compute.internal, executor 10):
ExecutorLostFailure (executor 10 exited caused by one of the running tasks)
Reason: Container killed by YARN for exceeding memory limits. 10.4 GB of
10.4 GB physical memory used. Consider boosting
spark.yarn.executor.memoryOverhead.
I tried to increase the spark.yarn.executor.memoryOverhead to 3000 which
delays the errors but eventually I get them before the end of the job. The
job eventually fails.
If I run the above job in scala everything works as expected (without having
to adjust the memoryOverhead)
import org.apache.spark.sql.functions.udf
val upper: String => String = _.toUpperCase
val df = spark.read.load("s3://some/parquet/dir/myfile.parquet")
val upperUDF = udf(upper)
val newdf = df.withColumn("test_field", upperUDF(col("std_useragent")))
newdf.write.parquet("/output.parquet")
Cpu utilisation is also very bad with pyspark.
Is this a known bug with pyspark and udfs or is it a matter of bad
configuration?
I've also raised a ticket in apache jira
https://issues.apache.org/jira/browse/SPARK-21935 which includes some
screenshots.
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