[SPARK-4006] Block Manager - Double Register Crash

This issue affects all versions since 0.7 up to (including) 1.1

In long running contexts, we encountered the situation of double register without a remove in between. The cause for that is unknown, and assumed a temp network issue.

However, since the second register is with a BlockManagerId on a different port, blockManagerInfo.contains() returns false, while blockManagerIdByExecutor returns Some. This inconsistency is caught in a conditional statement that does System.exit(1), which is a huge robustness issue for us.

The fix - simply remove the old id from both maps during register when this happens. We are mimicking the behavior of expireDeadHosts(), by doing local cleanup of the maps before trying to add new ones.

Also - added some logging for register and unregister.

https://issues.apache.org/jira/browse/SPARK-4006

Author: Tal Sliwowicz <[email protected]>

Closes #2854 from tsliwowicz/branch-0.9.2-block-mgr-removal and squashes the following commits:

95ae4db [Tal Sliwowicz] [SPARK-4006] In long running contexts, we encountered the situation of double registe...
81d69f0 [Tal Sliwowicz] fixed comment
efd93f2 [Tal Sliwowicz] In long running contexts, we encountered the situation of double register without a remove in between. The cause for that is unknown, and assumed a temp network issue.

Author: tsliwowicz

core/src/main/scala/org/apache/spark/storage/BlockManagerMasterActor.scala

@@ -160,6 +160,7 @@ class BlockManagerMasterActor(val isLocal: Boolean, conf: SparkConf) extends Act
         blockLocations.remove(locations)
       }
     }
+    logInfo(s"Removing block manager $blockManagerId")
   }
 
   private def expireDeadHosts() {
@@ -225,14 +226,18 @@ class BlockManagerMasterActor(val isLocal: Boolean, conf: SparkConf) extends Act
   private def register(id: BlockManagerId, maxMemSize: Long, slaveActor: ActorRef) {
     if (!blockManagerInfo.contains(id)) {
       blockManagerIdByExecutor.get(id.executorId) match {
-        case Some(manager) =>
-          // A block manager of the same executor already exists.
-          // This should never happen. Let's just quit.
-          logError("Got two different block manager registrations on " + id.executorId)
-          System.exit(1)
+        case Some(oldId) =>
+          // A block manager of the same executor already exists, so remove it (assumed dead)
+          logError("Got two different block manager registrations on same executor - " 
+              + s" will replace old one $oldId with new one $id")
+          removeExecutor(id.executorId)  
         case None =>
-          blockManagerIdByExecutor(id.executorId) = id
       }
+      logInfo("Registering block manager %s with %s RAM, %s".format(
+        id.hostPort, Utils.bytesToString(maxMemSize), id))
+      
+      blockManagerIdByExecutor(id.executorId) = id
+      
       blockManagerInfo(id) = new BlockManagerMasterActor.BlockManagerInfo(
         id, System.currentTimeMillis(), maxMemSize, slaveActor)
     }