They are deserialized out of Mongo but as a set of MongoResult objects and not as WebPages.
2014-10-10 15:17 GMT+02:00 Tyler Palsulich <[email protected]>: > > MongoDb doesn’t support Serializable interface. > > You're right. My mistake. Even if it was, Utf8 implementing Serializable > isn't an option. > > > I end up with a bunch of MongoResults instead of WebPages > > Are the WebPages "serialized" into Mongo, but not out of Mongo? > > Tyler > > On Fri, Oct 10, 2014 at 5:37 AM, Renato Marroquín Mogrovejo < > [email protected]> wrote: > > > Hi guys, > > > > So I have just tried putting and getting elements (Nutch's WebPage) > > entries specifically and everything works fine. So this is confusing, I > > guess Nutch is doing something in the middle there that may have to do > with > > the mapping file or something like it. Because I tried changing the key > > type (from String to Utf8) and gave an unrelated error saying that the > > collection hadn't been defined (which is not true), I would have expected > > to get a classCastException. And the other weird thing is that when > > performing a get using a query object I end up with a bunch of > MongoResults > > instead of WebPages. I think that is bug (or . . . a feature) that we are > > not aware of. Maybe Damian can help us out here. > > I will keep on pocking around, but gora-mongodb is getting the data in, > > and it is able to take it out. > > > > > > Renato M. > > > > 2014-10-10 9:17 GMT+02:00 Kiril Menshikov <[email protected]>: > > > >> Tyler, > >> > >> MongoDb doesn’t support Serializable interface. BasicBSONEncoder has > >> direct class checks. Unfortunately it's not enough to make Utf8 > >> serializable. > >> > >> -Kiril > >> > >> On Oct 9, 2014, at 21:44, Lewis John Mcgibbney < > [email protected]> > >> wrote: > >> > >> > Hi Folks, > >> > Whilst in the muddle of upgrading Nutch 2.3-SNAPSHOT to use Gora 0.5 > >> we've run into a problem when implementing the gora-mongodb stuff. > >> > The issue is described within the Jira issue [0]. This being said, > >> Kiril (CC'd) has stated quite clearly why this is happening. This is a > >> consequence of the following lines of the Nutch code base > >> > > >> > > >> > https://github.com/apache/nutch/blob/2.x/src/java/org/apache/nutch/fetcher/FetcherJob.java#L218 > >> > > >> > > >> > https://github.com/apache/nutch/blob/2.x/src/java/org/apache/nutch/parse/ParserJob.java#L274 > >> > > >> > > >> > https://github.com/apache/nutch/blob/2.x/src/java/org/apache/nutch/crawl/DbUpdaterJob.java#L128 > >> > > >> > and results in the following stack trace > >> > java.lang.IllegalArgumentException: can't serialize class > >> org.apache.avro.util.Utf8 > >> > at > org.bson.BasicBSONEncoder._putObjectField(BasicBSONEncoder.java:284) > >> > at org.bson.BasicBSONEncoder.putObject(BasicBSONEncoder.java:185) > >> > at org.bson.BasicBSONEncoder.putObject(BasicBSONEncoder.java:131) > >> > at com.mongodb.DefaultDBEncoder.writeObject(DefaultDBEncoder.java:33) > >> > at com.mongodb.OutMessage.putObject(OutMessage.java:289) > >> > at com.mongodb.OutMessage.writeQuery(OutMessage.java:211) > >> > at com.mongodb.OutMessage.query(OutMessage.java:86) > >> > at com.mongodb.DBCollectionImpl.find(DBCollectionImpl.java:81) > >> > at com.mongodb.DBCollectionImpl.find(DBCollectionImpl.java:66) > >> > at com.mongodb.DBCursor._check(DBCursor.java:458) > >> > at com.mongodb.DBCursor._hasNext(DBCursor.java:546) > >> > at com.mongodb.DBCursor.hasNext(DBCursor.java:571) > >> > at > >> > org.apache.gora.mongodb.query.MongoDBResult.nextInner(MongoDBResult.java:69) > >> > at org.apache.gora.query.impl.ResultBase.next(ResultBase.java:114) > >> > at > >> > org.apache.gora.mapreduce.GoraRecordReader.nextKeyValue(GoraRecordReader.java:119) > >> > at > >> > org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.nextKeyValue(MapTask.java:531) > >> > at > >> org.apache.hadoop.mapreduce.MapContext.nextKeyValue(MapContext.java:67) > >> > at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144) > >> > at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764) > >> > at org.apache.hadoop.mapred.MapTask.run(MapTask.java:364) > >> > at > >> > org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:223) > >> > at > >> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) > >> > at java.util.concurrent.FutureTask.run(FutureTask.java:262) > >> > 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:744) > >> > > >> > The cause is the following line (example from FetcherJob): > >> > filter.getOperands().add(new Utf8(batchId)); > >> > > >> > During serialization MongoDB doesn't know about Utf8 type. > >> > > >> > My question is now... should we remove the Utf8 from Nutch, or should > >> gora-mongodb handle this silently? > >> > > >> > Thanks for reading. > >> > Lewis > >> > > >> > [0] https://issues.apache.org/jira/browse/NUTCH-1843 > >> > > >> > -- > >> > Lewis > >> > >> > > >
