[NUTCH-1299] LinkRank inverter to ignore records without Node

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.4
• Fix Version/s: 1.5
• Patch Info: Patch Available
• Assignee: Markus Jelsma
• Reporter: Markus Jelsma
• Created: 06/Mar/12 00:35
• Updated: 22/May/13 03:53
• Resolved: 06/Mar/12 17:32

Description

No Node object is passed from the inverter's mapper to the reducer, which expects one, causing the following exception:

java.lang.NullPointerException
        at org.apache.nutch.scoring.webgraph.LinkRank$Inverter.reduce(LinkRank.java:409)
        at org.apache.nutch.scoring.webgraph.LinkRank$Inverter.reduce(LinkRank.java:356)
        at org.apache.hadoop.mapred.ReduceTask.runOldReducer(ReduceTask.java:519)
        at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:420)
        at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
        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:1083)
        at org.apache.hadoop.mapred.Child.main(Child.java:249)

This never happens unless you have a funky web graph. Our web graph changes frequently, adding and deleting records. It's likely a large number of records deleted from the outlink database is responsible for this. This error, however, only showed up now, a great deal of time after we began deleting records.