Hi Naveen, Quoting http://spark.apache.org/docs/latest/api/scala/index.html#org.apache.spark.SparkContext SparkContext is Main entry point for Spark functionality. A SparkContext represents the connection to a Spark cluster, and can be used to create RDDs, accumulators and broadcast variables on that cluster.
Only one SparkContext may be active per JVM. You must stop() the active SparkContext before creating a new one So stop ( ) shuts down the connection between Driver program and Spark master, and does some cleanup. Indeed, after calling this, you cannot do any operation on it or on any RDD created via this context. Regards, Kapil From: Naveen Madhire [mailto:vmadh...@umail.iu.edu] Sent: 31 December 2014 22:08 To: RK Cc: user@spark.apache.org Subject: Re: Fwd: Sample Spark Program Error Yes. The exception is gone now after adding stop() at the end. Can you please tell me what this stop() does at the end. Does it disable the spark context. On Wed, Dec 31, 2014 at 10:09 AM, RK <prk...@yahoo.com<mailto:prk...@yahoo.com>> wrote: If you look at your program output closely, you can see the following output. Lines with a: 24, Lines with b: 15 The exception seems to be happening with Spark cleanup after executing your code. Try adding sc.stop() at the end of your program to see if the exception goes away. On Wednesday, December 31, 2014 6:40 AM, Naveen Madhire <vmadh...@umail.iu.edu<mailto:vmadh...@umail.iu.edu>> wrote: Hi All, I am trying to run a sample Spark program using Scala SBT, Below is the program, def main(args: Array[String]) { val logFile = "E:/ApacheSpark/usb/usb/spark/bin/README.md" // Should be some file on your system val sc = new SparkContext("local", "Simple App", "E:/ApacheSpark/usb/usb/spark/bin",List("target/scala-2.10/sbt2_2.10-1.0.jar")) val logData = sc.textFile(logFile, 2).cache() val numAs = logData.filter(line => line.contains("a")).count() val numBs = logData.filter(line => line.contains("b")).count() println("Lines with a: %s, Lines with b: %s".format(numAs, numBs)) } Below is the error log, 14/12/30 23:20:21 INFO rdd.HadoopRDD: Input split: file:/E:/ApacheSpark/usb/usb/spark/bin/README.md:0+673 14/12/30 23:20:21 INFO storage.MemoryStore: ensureFreeSpace(2032) called with curMem=34047, maxMem=280248975 14/12/30 23:20:21 INFO storage.MemoryStore: Block rdd_1_0 stored as values in memory (estimated size 2032.0 B, free 267.2 MB) 14/12/30 23:20:21 INFO storage.BlockManagerInfo: Added rdd_1_0 in memory on zealot:61452 (size: 2032.0 B, free: 267.3 MB) 14/12/30 23:20:21 INFO storage.BlockManagerMaster: Updated info of block rdd_1_0 14/12/30 23:20:21 INFO executor.Executor: Finished task 0.0 in stage 0.0 (TID 0). 2300 bytes result sent to driver 14/12/30 23:20:21 INFO scheduler.TaskSetManager: Starting task 1.0 in stage 0.0 (TID 1, localhost, PROCESS_LOCAL, 1264 bytes) 14/12/30 23:20:21 INFO executor.Executor: Running task 1.0 in stage 0.0 (TID 1) 14/12/30 23:20:21 INFO spark.CacheManager: Partition rdd_1_1 not found, computing it 14/12/30 23:20:21 INFO rdd.HadoopRDD: Input split: file:/E:/ApacheSpark/usb/usb/spark/bin/README.md:673+673 14/12/30 23:20:21 INFO scheduler.TaskSetManager: Finished task 0.0 in stage 0.0 (TID 0) in 3507 ms on localhost (1/2) 14/12/30 23:20:21 INFO storage.MemoryStore: ensureFreeSpace(1912) called with curMem=36079, maxMem=280248975 14/12/30 23:20:21 INFO storage.MemoryStore: Block rdd_1_1 stored as values in memory (estimated size 1912.0 B, free 267.2 MB) 14/12/30 23:20:21 INFO storage.BlockManagerInfo: Added rdd_1_1 in memory on zealot:61452 (size: 1912.0 B, free: 267.3 MB) 14/12/30 23:20:21 INFO storage.BlockManagerMaster: Updated info of block rdd_1_1 14/12/30 23:20:21 INFO executor.Executor: Finished task 1.0 in stage 0.0 (TID 1). 2300 bytes result sent to driver 14/12/30 23:20:21 INFO scheduler.TaskSetManager: Finished task 1.0 in stage 0.0 (TID 1) in 261 ms on localhost (2/2) 14/12/30 23:20:21 INFO scheduler.TaskSchedulerImpl: Removed TaskSet 0.0, whose tasks have all completed, from pool 14/12/30 23:20:21 INFO scheduler.DAGScheduler: Stage 0 (count at Test1.scala:19) finished in 3.811 s 14/12/30 23:20:21 INFO spark.SparkContext: Job finished: count at Test1.scala:19, took 3.997365232 s 14/12/30 23:20:21 INFO spark.SparkContext: Starting job: count at Test1.scala:20 14/12/30 23:20:21 INFO scheduler.DAGScheduler: Got job 1 (count at Test1.scala:20) with 2 output partitions (allowLocal=false) 14/12/30 23:20:21 INFO scheduler.DAGScheduler: Final stage: Stage 1(count at Test1.scala:20) 14/12/30 23:20:21 INFO scheduler.DAGScheduler: Parents of final stage: List() 14/12/30 23:20:21 INFO scheduler.DAGScheduler: Missing parents: List() 14/12/30 23:20:21 INFO scheduler.DAGScheduler: Submitting Stage 1 (FilteredRDD[3] at filter at Test1.scala:20), which has no missing parents 14/12/30 23:20:21 INFO storage.MemoryStore: ensureFreeSpace(2600) called with curMem=37991, maxMem=280248975 14/12/30 23:20:21 INFO storage.MemoryStore: Block broadcast_2 stored as values in memory (estimated size 2.5 KB, free 267.2 MB) 14/12/30 23:20:21 INFO scheduler.DAGScheduler: Submitting 2 missing tasks from Stage 1 (FilteredRDD[3] at filter at Test1.scala:20) 14/12/30 23:20:21 INFO scheduler.TaskSchedulerImpl: Adding task set 1.0 with 2 tasks 14/12/30 23:20:21 INFO scheduler.TaskSetManager: Starting task 0.0 in stage 1.0 (TID 2, localhost, ANY, 1264 bytes) 14/12/30 23:20:21 INFO executor.Executor: Running task 0.0 in stage 1.0 (TID 2) 14/12/30 23:20:21 INFO storage.BlockManager: Found block rdd_1_0 locally 14/12/30 23:20:21 INFO executor.Executor: Finished task 0.0 in stage 1.0 (TID 2). 1731 bytes result sent to driver 14/12/30 23:20:21 INFO scheduler.TaskSetManager: Starting task 1.0 in stage 1.0 (TID 3, localhost, ANY, 1264 bytes) 14/12/30 23:20:21 INFO executor.Executor: Running task 1.0 in stage 1.0 (TID 3) 14/12/30 23:20:21 INFO storage.BlockManager: Found block rdd_1_1 locally 14/12/30 23:20:21 INFO executor.Executor: Finished task 1.0 in stage 1.0 (TID 3). 1731 bytes result sent to driver 14/12/30 23:20:21 INFO scheduler.TaskSetManager: Finished task 1.0 in stage 1.0 (TID 3) in 7 ms on localhost (1/2) 14/12/30 23:20:21 INFO scheduler.TaskSetManager: Finished task 0.0 in stage 1.0 (TID 2) in 16 ms on localhost (2/2) 14/12/30 23:20:21 INFO scheduler.DAGScheduler: Stage 1 (count at Test1.scala:20) finished in 0.016 s 14/12/30 23:20:21 INFO scheduler.TaskSchedulerImpl: Removed TaskSet 1.0, whose tasks have all completed, from pool 14/12/30 23:20:21 INFO spark.SparkContext: Job finished: count at Test1.scala:20, took 0.041709824 s Lines with a: 24, Lines with b: 15 14/12/30 23:20:21 ERROR util.Utils: Uncaught exception in thread SparkListenerBus java.lang.InterruptedException at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1301) at java.util.concurrent.Semaphore.acquire(Semaphore.java:317) at org.apache.spark.scheduler.LiveListenerBus$$anon$1$$anonfun$run$1.apply$mcV$sp(LiveListenerBus.scala:48) at org.apache.spark.scheduler.LiveListenerBus$$anon$1$$anonfun$run$1.apply(LiveListenerBus.scala:47) at org.apache.spark.scheduler.LiveListenerBus$$anon$1$$anonfun$run$1.apply(LiveListenerBus.scala:47) at org.apache.spark.util.Utils$.logUncaughtExceptions(Utils.scala:1311) [success] Total time: 12 s, completed Dec 30, 2014 11:20:21 PM at org.apache.spark.scheduler.LiveListenerBus$$anon$1.run(LiveListenerBus.scala:46) 14/12/30 23:20:21 ERROR spark.ContextCleaner: Error in cleaning thread java.lang.InterruptedException at java.lang.Object.wait(Native Method) at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:135) at org.apache.spark.ContextCleaner$$anonfun$org$apache$spark$ContextCleaner$$keepCleaning$1.apply$mcV$sp(ContextCleaner.scala:136) at org.apache.spark.ContextCleaner$$anonfun$org$apache$spark$ContextCleaner$$keepCleaning$1.apply(ContextCleaner.scala:134) at org.apache.spark.ContextCleaner$$anonfun$org$apache$spark$ContextCleaner$$keepCleaning$1.apply(ContextCleaner.scala:134) at org.apache.spark.util.Utils$.logUncaughtExceptions(Utils.scala:1311) at org.apache.spark.ContextCleaner.org<http://org.apache.spark.contextcleaner.org/>$apache$spark$ContextCleaner$$keepCleaning(ContextCleaner.scala:133) at org.apache.spark.ContextCleaner$$anon$3.run(ContextCleaner.scala:65) 14/12/30 23:20:21 INFO network.ConnectionManager: Selector thread was interrupted! 14/12/30 23:20:21 INFO storage.BlockManager: Removing broadcast 2 14/12/30 23:20:21 INFO storage.BlockManager: Removing block broadcast_2 14/12/30 23:20:21 INFO storage.MemoryStore: Block broadcast_2 of size 2600 dropped from memory (free 280210984) 14/12/30 23:20:21 INFO spark.ContextCleaner: Cleaned broadcast 2 Please let me know any pointers to debug the error. Thanks a lot.
