Josh Rosen created SPARK-6492:
---------------------------------
Summary: Spark can freeze / deadlock when
DAGSchedulerEventProcessLoop dies
Key: SPARK-6492
URL: https://issues.apache.org/jira/browse/SPARK-6492
Project: Spark
Issue Type: Bug
Components: Spark Core
Affects Versions: 1.3.0, 1.4.0
Reporter: Josh Rosen
Priority: Critical
A deadlock can occur when DAGScheduler death causes a SparkContext to be shut
down while user code is concurrently racing to stop the SparkContext in a
finally block.
For example:
{code}
try {
sc = new SparkContext("local", "test")
// start running a job that causes the DAGSchedulerEventProcessor to crash
someRDD.doStuff()
}
} finally {
sc.stop() // stop the sparkcontext once the failure in DAGScheduler causes
the above job to fail with an exception
}
{code}
This leads to a deadlock. The event processor thread tries to lock on the
{{SparkContext.SPARK_CONTEXT_CONSTRUCTOR_LOCK}} and becomes blocked because the
thread that holds that lock is waiting for the event processor thread to join:
{code}
"dag-scheduler-event-loop" daemon prio=5 tid=0x00007ffa69456000 nid=0x9403
waiting for monitor entry [0x00000001223ad000]
java.lang.Thread.State: BLOCKED (on object monitor)
at org.apache.spark.SparkContext.stop(SparkContext.scala:1398)
- waiting to lock <0x00000007f5037b08> (a java.lang.Object)
at
org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onError(DAGScheduler.scala:1412)
at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:52)
{code}
{code}
"pool-1-thread-1-ScalaTest-running-SparkContextSuite" prio=5
tid=0x00007ffa69864800 nid=0x5903 in Object.wait() [0x00000001202dc000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000007f4b28000> (a
org.apache.spark.util.EventLoop$$anon$1)
at java.lang.Thread.join(Thread.java:1281)
- locked <0x00000007f4b28000> (a
org.apache.spark.util.EventLoop$$anon$1)
at java.lang.Thread.join(Thread.java:1355)
at org.apache.spark.util.EventLoop.stop(EventLoop.scala:79)
at org.apache.spark.scheduler.DAGScheduler.stop(DAGScheduler.scala:1352)
at org.apache.spark.SparkContext.stop(SparkContext.scala:1405)
- locked <0x00000007f5037b08> (a java.lang.Object)
[...]
{code}
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