Hi Aapo,

Thanks for the error report. I think you found a bug. Can you try the included patch and see if the problem goes away? I got it to pass local and MR unittests.


On 9/30/11 4:08 PM, Aapo Kyrola wrote:

occasionally (maybe one time in four), my giraph run fails because of the below RuntimeException.
According to code, it should never happen:

if (msgMap == null) { // should never happen after constructor throw new RuntimeException( "sendMessage: msgMap did not exist for " + addr + " for vertex " + destVertex); }

This happens during superstep 1 (second superstep). My application actually *adds* edges on superstep 1 (to make every out-edge also an in-edge of the destination), but since I am running only on 3 workers, I am surprised if every worker would not had been registered in the RPC layer initially.

One hypothesis is that Hadoop does something funny, because one of my server was under heavy load. Maybe Hadoop launched another worker to replace a slow worker? Can it happen?

java.lang.RuntimeException: sendMessage: msgMap did not exist for [hostname].ml.cmu.edu:30003 for vertex 875713 at org.apache.giraph.comm.BasicRPCCommunications.sendMessageReq(BasicRPCCommunications.java:825) at org.apache.giraph.graph.BasicVertex.sendMsg(BasicVertex.java:179) at edu.cmu.selectlab.BP.BinaryBPVertex.compute(BinaryBPVertex.java:94)
        at org.apache.giraph.graph.GraphMapper.map(GraphMapper.java:624)
        at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
        at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:763)
        at org.apache.hadoop.mapred.MapTask.run(MapTask.java:369)
        at org.apache.hadoop.mapred.Child$4.run(Child.java:259)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1059)
        at org.apache.hadoop.mapred.Child.main(Child.java:253)

Aapo Kyrola
Ph.D. student, http://www.cs.cmu.edu/~akyrola <http://www.cs.cmu.edu/%7Eakyrola>

Index: src/main/java/org/apache/giraph/graph/GraphMapper.java
--- src/main/java/org/apache/giraph/graph/GraphMapper.java      (revision 
+++ src/main/java/org/apache/giraph/graph/GraphMapper.java      (working copy)
@@ -562,7 +562,7 @@
                           " maxMem=" + Runtime.getRuntime().maxMemory() +
                           " freeMem=" + Runtime.getRuntime().freeMemory());
-            if ((superstep > BspService.INPUT_SUPERSTEP) &&
+            if ((superstep >= BspService.INPUT_SUPERSTEP) &&
                     (commService == null)) {
                 if (LOG.isInfoEnabled()) {
                     LOG.info("map: Starting communication service on " +

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