[SPARK-5425] ConcurrentModificationException during SparkConf creation

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.1.1, 1.2.0
• Fix Version/s: 1.1.2, 1.2.2, 1.3.0
• Component/s: Spark Core
• Assignee: Jacek Lewandowski
• Reporter: Jacek Lewandowski
• Created: 27/Jan/15 09:58
• Updated: 08/Feb/15 03:17
• Resolved: 08/Feb/15 03:17

Description

This fragment of code:

  if (loadDefaults) {
    // Load any spark.* system properties
    for ((k, v) <- System.getProperties.asScala if k.startsWith("spark.")) {
      settings(k) = v
    }
  }

causes

ERROR 09:43:15  SparkMaster service caused error in state STARTINGjava.util.ConcurrentModificationException: null
	at java.util.Hashtable$Enumerator.next(Hashtable.java:1167) ~[na:1.7.0_60]
	at scala.collection.convert.Wrappers$JPropertiesWrapper$$anon$3.next(Wrappers.scala:458) ~[scala-library-2.10.4.jar:na]
	at scala.collection.convert.Wrappers$JPropertiesWrapper$$anon$3.next(Wrappers.scala:454) ~[scala-library-2.10.4.jar:na]
	at scala.collection.Iterator$class.foreach(Iterator.scala:727) ~[scala-library-2.10.4.jar:na]
	at scala.collection.AbstractIterator.foreach(Iterator.scala:1157) ~[scala-library-2.10.4.jar:na]
	at scala.collection.IterableLike$class.foreach(IterableLike.scala:72) ~[scala-library-2.10.4.jar:na]
	at scala.collection.AbstractIterable.foreach(Iterable.scala:54) ~[scala-library-2.10.4.jar:na]
	at scala.collection.TraversableLike$WithFilter.foreach(TraversableLike.scala:771) ~[scala-library-2.10.4.jar:na]
	at org.apache.spark.SparkConf.<init>(SparkConf.scala:53) ~[spark-core_2.10-1.2.1_dse-20150121.075638-2.jar:1.2.1_dse-SNAPSHOT]
	at org.apache.spark.SparkConf.<init>(SparkConf.scala:47) ~[spark-core_2.10-1.2.1_dse-20150121.075638-2.jar:1.2.1_dse-SNAPSHOT]

when there is another thread which modifies system properties at the same time.

This bug https://issues.scala-lang.org/browse/SI-7775 is somehow related to the issue and shows that the problem has been also found elsewhere.

Issue Links

• is related to: SPARK-1010 Update all unit tests to use SparkConf instead of system properties
• links to: [Github] Pull Request #4220 (jacek-lewandowski)
• links to: [Github] Pull Request #4221 (jacek-lewandowski)
• links to: [Github] Pull Request #4222 (jacek-lewandowski)