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Posted to issues@spark.apache.org by "Ruslan Yushchenko (JIRA)" <ji...@apache.org> on 2019/06/12 07:32:01 UTC
[jira] [Created] (SPARK-28016) Spark hangs when an execution plan
has many projections on nested structs
Ruslan Yushchenko created SPARK-28016:
-----------------------------------------
Summary: Spark hangs when an execution plan has many projections on nested structs
Key: SPARK-28016
URL: https://issues.apache.org/jira/browse/SPARK-28016
Project: Spark
Issue Type: Bug
Components: Optimizer
Affects Versions: 2.4.3
Environment: Tried in
* Spark 2.2.1, Spark 2.4.3 in local mode on Linux, MasOS and Windows
* Spark 2.4.3 / Yarn on a Linux cluster
Reporter: Ruslan Yushchenko
Spark applications freeze on execution plan optimization stage (Catalyst) when a logical execution plan contains a lot of projections that operate on nested struct fields.
2 Spark Applications are attached. One demonstrates the issue, the other demonstrates a workaround. Also, an archive is attached where these jobs are packages as a Maven Project.
To reproduce the attached Spark App does the following:
* A small dataframe is created from a JSON example.
* A nested withColumn map transformation is used to apply a transformation on a struct field and create a new struct field. The code for this transformation is also attached.
* Once more than 11 such transformations are applied the Catalyst optimizer freezes on optimizing the execution plan
{code:scala}
package za.co.absa.spark.app
import org.apache.spark.sql._
import org.apache.spark.sql.functions._
object SparkApp1Issue {
// A sample data for a dataframe with nested structs
val sample =
"""
|{
| "strings": {
| "simple": "Culpa repellat nesciunt accusantium",
| "all_random": "DESebo8d%fL9sX@AzVin",
| "whitespaces": " q bb l "
| },
| "numerics": {
| "small_positive": 722,
| "small_negative": -660,
| "big_positive": 669223368251997,
| "big_negative": -161176863305841,
| "zero": 0
| }
|}
""".stripMargin ::
"""{
| "strings": {
| "simple": "Accusamus quia vel deleniti",
| "all_random": "rY&n9UnVcD*KS]jPBpa[",
| "whitespaces": " t e t rp z p"
| },
| "numerics": {
| "small_positive": 268,
| "small_negative": -134,
| "big_positive": 768990048149640,
| "big_negative": -684718954884696,
| "zero": 0
| }
|}
|""".stripMargin ::
"""{
| "strings": {
| "simple": "Quia numquam deserunt delectus rem est",
| "all_random": "GmRdQlE4Avn1hSlVPAH",
| "whitespaces": " c sa yv drf "
| },
| "numerics": {
| "small_positive": 909,
| "small_negative": -363,
| "big_positive": 592517494751902,
| "big_negative": -703224505589638,
| "zero": 0
| }
|}
|""".stripMargin :: Nil
/**
* This Spark Job demonstrates an issue of execution plan freezing when there are a lot of projections
* involving nested structs in an execution plan.
*
* The example works as follows:
* - A small dataframe is created from a JSON example above
* - A nested withColumn map transformation is used to apply a transformation on a struct field and create
* a new struct field.
* - Once more than 11 such transformations are applied the Catalyst optimizer freezes on optimizing
* the execution plan
*/
def main(args: Array[String]): Unit = {
val sparkBuilder = SparkSession.builder().appName("Nested Projections Issue")
val spark = sparkBuilder
.master("local[4]")
.getOrCreate()
import spark.implicits._
import za.co.absa.spark.utils.NestedOps.DataSetWrapper
val df = spark.read.json(sample.toDS)
// Apply several uppercase and negation transformations
val dfOutput = df
.nestedWithColumnMap("strings.simple", "strings.uppercase1", c => upper(c))
.nestedWithColumnMap("strings.all_random", "strings.uppercase2", c => upper(c))
.nestedWithColumnMap("strings.whitespaces", "strings.uppercase3", c => upper(c))
.nestedWithColumnMap("numerics.small_positive", "numerics.num1", c => -c)
.nestedWithColumnMap("numerics.small_negative", "numerics.num2", c => -c)
.nestedWithColumnMap("numerics.big_positive", "numerics.num3", c => -c)
.nestedWithColumnMap("numerics.big_negative", "numerics.num4", c => -c)
.nestedWithColumnMap("numerics.small_positive", "numerics.num5", c => -c)
.nestedWithColumnMap("numerics.small_negative", "numerics.num6", c => -c)
.nestedWithColumnMap("numerics.big_positive", "numerics.num7", c => -c)
.nestedWithColumnMap("numerics.big_negative", "numerics.num8", c => -c)
// Uncommenting the line below will cause Catalyst to freeze completely
//.nestedWithColumnMap("numerics.big_negative", "numerics.num9", c => -c)
dfOutput.printSchema()
dfOutput.explain(true)
dfOutput.show
}
}
{code}
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