slave lost and very slow join in spark - performance

Question

I did a join of two dataframes on one common column and then ran a show method:
df= df1.join(df2, df1.col1== df2.col2, 'inner')
df.show()
Then join ran very slow and finally raise an error: slave lost.
Py4JJavaError: An error occurred while calling o109.showString.
: org.apache.spark.SparkException: Job aborted due to stage failure: Task 0 in stage 8.0 failed 4 times, most recent failure: Lost task 0.3 in stage 8.0 : ExecutorLostFailure (executor 1 exited caused by one of the running tasks) Reason: Slave lost
Driver stacktrace:
at
org.apache.spark.scheduler.DAGScheduler.org$apache$spark$scheduler$DAGScheduler$$failJobAndIndependentStages(DAGScheduler.scala:1431)
at
org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1419)
at
org.apache.spark.scheduler.DAGScheduler$$anonfun$abortStage$1.apply(DAGScheduler.scala:1418)
at
scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
at
org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:1418)
at
org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:799)
at
org.apache.spark.scheduler.DAGScheduler$$anonfun$handleTaskSetFailed$1.apply(DAGScheduler.scala:799)
at scala.Option.foreach(Option.scala:236) at
org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:799)
at
org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:1640)
at
org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1599)
at
org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:1588)
at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:48)
at
org.apache.spark.scheduler.DAGScheduler.runJob(DAGScheduler.scala:620)
at org.apache.spark.SparkContext.runJob(SparkContext.scala:1832) at
org.apache.spark.SparkContext.runJob(SparkContext.scala:1845) at
org.apache.spark.SparkContext.runJob(SparkContext.scala:1858) at
org.apache.spark.sql.execution.SparkPlan.executeTake(SparkPlan.scala:212)
at
org.apache.spark.sql.execution.Limit.executeCollect(basicOperators.scala:165)
at
org.apache.spark.sql.execution.SparkPlan.executeCollectPublic(SparkPlan.scala:174)
at
org.apache.spark.sql.DataFrame$$anonfun$org$apache$spark$sql$DataFrame$$execute$1$1.apply(DataFrame.scala:1499)
at
org.apache.spark.sql.DataFrame$$anonfun$org$apache$spark$sql$DataFrame$$execute$1$1.apply(DataFrame.scala:1499)
at
org.apache.spark.sql.execution.SQLExecution$.withNewExecutionId(SQLExecution.scala:56)
at
org.apache.spark.sql.DataFrame.withNewExecutionId(DataFrame.scala:2086)
at
org.apache.spark.sql.DataFrame.org$apache$spark$sql$DataFrame$$execute$1(DataFrame.scala:1498)
at
org.apache.spark.sql.DataFrame.org$apache$spark$sql$DataFrame$$collect(DataFrame.scala:1505)
at
org.apache.spark.sql.DataFrame$$anonfun$head$1.apply(DataFrame.scala:1375)
at
org.apache.spark.sql.DataFrame$$anonfun$head$1.apply(DataFrame.scala:1374)
at org.apache.spark.sql.DataFrame.withCallback(DataFrame.scala:2099)
at org.apache.spark.sql.DataFrame.head(DataFrame.scala:1374) at
org.apache.spark.sql.DataFrame.take(DataFrame.scala:1456) at
org.apache.spark.sql.DataFrame.showString(DataFrame.scala:170) at
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498) at
py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:231) at
py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:381) at
py4j.Gateway.invoke(Gateway.java:259) at
py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:133)
at py4j.commands.CallCommand.execute(CallCommand.java:79) at
py4j.GatewayConnection.run(GatewayConnection.java:209) at
java.lang.Thread.run(Thread.java:745)
After some search, it seems this is a memory related issue. Then I increased repartition to 3000, increased executor memory,increased memoryOverhead, but still no luck, I got the same slave lost error. During df.show(), I found one of the execuctor shuffle write size is very high, the others were not so high.
Any clue?
Thanks

Answer 1

If using scala try
val df = df1.join(df2,Seq("column name"))
if pyspark
df = df1.join(df2,["columnname"])
or
df = df1.join(df2,df1.columnname == df2.columnname)
display(df)
If trying to do same in pyspark - sql
df1.createOrReplaceTempView("left_test_table")
df2..createOrReplaceTempView("right_test_table")
left <- sql(sqlContext, "SELECT * FROM left_test_table")
right <- sql(sqlContext, "SELECT * FROM right_test_table")
head(drop(join(left, right), left$name))