[NUTCH-1596] HeadingsParseFilter not thread safe

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.7
• Fix Version/s: 1.8
• Assignee: Markus Jelsma
• Reporter: Markus Jelsma
• Created: 02/Jul/13 09:08
• Updated: 13/Mar/24 14:51
• Resolved: 04/Jul/13 11:14

Description

The NodeWalker used by the HeadingsParseFilter sometimes reports a NullPointerException.

2013-07-02 11:02:09,428 WARN  parse.ParseUtil - Error parsing .... with org.apache.nutch.parse.tika.TikaParser@2c8b586a
java.util.concurrent.ExecutionException: java.lang.NullPointerException
        at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:262)
        at java.util.concurrent.FutureTask.get(FutureTask.java:119)
        at org.apache.nutch.parse.ParseUtil.runParser(ParseUtil.java:162)
        at org.apache.nutch.parse.ParseUtil.parse(ParseUtil.java:93)
        at org.apache.nutch.fetcher.Fetcher$FetcherThread.output(Fetcher.java:963)
        at org.apache.nutch.fetcher.Fetcher$FetcherThread.run(Fetcher.java:722)
Caused by: java.lang.NullPointerException
        at org.apache.xerces.dom.ParentNode.nodeListItem(Unknown Source)
        at org.apache.xerces.dom.ParentNode.item(Unknown Source)
        at org.apache.nutch.util.NodeWalker.nextNode(NodeWalker.java:75)
        at org.apache.nutch.parse.headings.HeadingsParseFilter.getElement(HeadingsParseFilter.java:84)
        at org.apache.nutch.parse.headings.HeadingsParseFilter.filter(HeadingsParseFilter.java:47)
        at org.apache.nutch.parse.HtmlParseFilters.filter(HtmlParseFilters.java:98)
        at org.apache.nutch.parse.tika.TikaParser.getParse(TikaParser.java:210)
        at org.apache.nutch.parse.ParseCallable.call(ParseCallable.java:35)
        at org.apache.nutch.parse.ParseCallable.call(ParseCallable.java:24)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
        at java.util.concurrent.FutureTask.run(FutureTask.java:166)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:722)

This is strange because it only rarely fails and the nextNode() method checks hasNext() and there is no concurrent access if i'm correct.