Re: NullWritable not serializable
Hi,
The test case is separated out as follows. The call to rdd2.first() breaks when
spark version is changed to 1.1.0, reporting exception NullWritable not
serializable. However, the same test passed with spark 1.0.2. The pom.xml file
is attached. The test data README.md was copied from spark.
Thanks,
Du
-
package com.company.project.test
import org.scalatest._
class WritableTestSuite extends FunSuite {
test(generated sequence file should be readable from spark) {
import org.apache.hadoop.io.{NullWritable, Text}
import org.apache.spark.{SparkContext, SparkConf}
import org.apache.spark.SparkContext._
val conf = new SparkConf(false).setMaster(local).setAppName(test data
exchange with spark)
val sc = new SparkContext(conf)
val rdd = sc.textFile(README.md)
val res = rdd.map(x = (NullWritable.get(), new Text(x)))
res.saveAsSequenceFile(./test_data)
val rdd2 = sc.sequenceFile(./test_data, classOf[NullWritable],
classOf[Text])
assert(rdd.first == rdd2.first._2.toString)
}
}
From: Matei Zaharia matei.zaha...@gmail.commailto:matei.zaha...@gmail.com
Date: Monday, September 15, 2014 at 10:52 PM
To: Du Li l...@yahoo-inc.commailto:l...@yahoo-inc.com
Cc: user@spark.apache.orgmailto:user@spark.apache.org
user@spark.apache.orgmailto:user@spark.apache.org,
d...@spark.apache.orgmailto:d...@spark.apache.org
d...@spark.apache.orgmailto:d...@spark.apache.org
Subject: Re: NullWritable not serializable
Can you post the exact code for the test that worked in 1.0? I can't think of
much that could've changed. The one possibility is if we had some operations
that were computed locally on the driver (this happens with things like first()
and take(), which will try to do the first partition locally). But generally
speaking these operations should *not* work over a network, so you'll have to
make sure that you only send serializable types through shuffles or collects,
or use a serialization framework like Kryo that might be okay with Writables.
Matei
On September 15, 2014 at 9:13:13 PM, Du Li
(l...@yahoo-inc.commailto:l...@yahoo-inc.com) wrote:
Hi Matei,
Thanks for your reply.
The Writable classes have never been serializable and this is why it is weird.
I did try as you suggested to map the Writables to integers and strings. It
didn’t pass, either. Similar exceptions were thrown except that the messages
became IntWritable, Text are not serializable. The reason is in the implicits
defined in the SparkContext object that convert those values into their
corresponding Writable classes before saving the data in sequence file.
My original code was actual some test cases to try out SequenceFile related
APIs. The tests all passed when the spark version was specified as 1.0.2. But
this one failed after I changed the spark version to 1.1.0 the new release,
nothing else changed. In addition, it failed when I called rdd2.collect(),
take(1), and first(). But it worked fine when calling rdd2.count(). As you can
see, count() does not need to serialize and ship data while the other three
methods do.
Do you recall any difference between spark 1.0 and 1.1 that might cause this
problem?
Thanks,
Du
From: Matei Zaharia matei.zaha...@gmail.commailto:matei.zaha...@gmail.com
Date: Friday, September 12, 2014 at 9:10 PM
To: Du Li l...@yahoo-inc.com.invalidmailto:l...@yahoo-inc.com.invalid,
user@spark.apache.orgmailto:user@spark.apache.org
user@spark.apache.orgmailto:user@spark.apache.org,
d...@spark.apache.orgmailto:d...@spark.apache.org
d...@spark.apache.orgmailto:d...@spark.apache.org
Subject: Re: NullWritable not serializable
Hi Du,
I don't think NullWritable has ever been serializable, so you must be doing
something differently from your previous program. In this case though, just use
a map() to turn your Writables to serializable types (e.g. null and String).
Matie
On September 12, 2014 at 8:48:36 PM, Du Li
(l...@yahoo-inc.com.invalidmailto:l...@yahoo-inc.com.invalid) wrote:
Hi,
I was trying the following on spark-shell (built with apache master and hadoop
2.4.0). Both calling rdd2.collect and calling rdd3.collect threw
java.io.NotSerializableException: org.apache.hadoop.io.NullWritable.
I got the same problem in similar code of my app which uses the newly released
Spark 1.1.0 under hadoop 2.4.0. Previously it worked fine with spark 1.0.2
under either hadoop 2.40 and 0.23.10.
Anybody knows what caused the problem?
Thanks,
Du
import org.apache.hadoop.io.{NullWritable, Text}
val rdd = sc.textFile(README.md)
val res = rdd.map(x = (NullWritable.get(), new Text(x)))
res.saveAsSequenceFile(./test_data)
val rdd2 = sc.sequenceFile(./test_data, classOf[NullWritable], classOf[Text])
rdd2.collect
val rdd3 = sc.sequenceFile[NullWritable,Text](./test_data)
rdd3.collect
pom.xml
Description: pom.xml
-
To unsubscribe, e-mail: user-unsubscr...@spark.apache.org
For additional
Re: NullWritable not serializable
Hi Matei,
Thanks for your reply.
The Writable classes have never been serializable and this is why it is weird.
I did try as you suggested to map the Writables to integers and strings. It
didn’t pass, either. Similar exceptions were thrown except that the messages
became IntWritable, Text are not serializable. The reason is in the implicits
defined in the SparkContext object that convert those values into their
corresponding Writable classes before saving the data in sequence file.
My original code was actual some test cases to try out SequenceFile related
APIs. The tests all passed when the spark version was specified as 1.0.2. But
this one failed after I changed the spark version to 1.1.0 the new release,
nothing else changed. In addition, it failed when I called rdd2.collect(),
take(1), and first(). But it worked fine when calling rdd2.count(). As you can
see, count() does not need to serialize and ship data while the other three
methods do.
Do you recall any difference between spark 1.0 and 1.1 that might cause this
problem?
Thanks,
Du
From: Matei Zaharia matei.zaha...@gmail.commailto:matei.zaha...@gmail.com
Date: Friday, September 12, 2014 at 9:10 PM
To: Du Li l...@yahoo-inc.com.invalidmailto:l...@yahoo-inc.com.invalid,
user@spark.apache.orgmailto:user@spark.apache.org
user@spark.apache.orgmailto:user@spark.apache.org,
d...@spark.apache.orgmailto:d...@spark.apache.org
d...@spark.apache.orgmailto:d...@spark.apache.org
Subject: Re: NullWritable not serializable
Hi Du,
I don't think NullWritable has ever been serializable, so you must be doing
something differently from your previous program. In this case though, just use
a map() to turn your Writables to serializable types (e.g. null and String).
Matie
On September 12, 2014 at 8:48:36 PM, Du Li
(l...@yahoo-inc.com.invalidmailto:l...@yahoo-inc.com.invalid) wrote:
Hi,
I was trying the following on spark-shell (built with apache master and hadoop
2.4.0). Both calling rdd2.collect and calling rdd3.collect threw
java.io.NotSerializableException: org.apache.hadoop.io.NullWritable.
I got the same problem in similar code of my app which uses the newly released
Spark 1.1.0 under hadoop 2.4.0. Previously it worked fine with spark 1.0.2
under either hadoop 2.40 and 0.23.10.
Anybody knows what caused the problem?
Thanks,
Du
import org.apache.hadoop.io.{NullWritable, Text}
val rdd = sc.textFile(README.md)
val res = rdd.map(x = (NullWritable.get(), new Text(x)))
res.saveAsSequenceFile(./test_data)
val rdd2 = sc.sequenceFile(./test_data, classOf[NullWritable], classOf[Text])
rdd2.collect
val rdd3 = sc.sequenceFile[NullWritable,Text](./test_data)
rdd3.collect
Re: NullWritable not serializable
Can you post the exact code for the test that worked in 1.0? I can't think of
much that could've changed. The one possibility is if we had some operations
that were computed locally on the driver (this happens with things like first()
and take(), which will try to do the first partition locally). But generally
speaking these operations should *not* work over a network, so you'll have to
make sure that you only send serializable types through shuffles or collects,
or use a serialization framework like Kryo that might be okay with Writables.
Matei
On September 15, 2014 at 9:13:13 PM, Du Li (l...@yahoo-inc.com) wrote:
Hi Matei,
Thanks for your reply.
The Writable classes have never been serializable and this is why it is weird.
I did try as you suggested to map the Writables to integers and strings. It
didn’t pass, either. Similar exceptions were thrown except that the messages
became IntWritable, Text are not serializable. The reason is in the implicits
defined in the SparkContext object that convert those values into their
corresponding Writable classes before saving the data in sequence file.
My original code was actual some test cases to try out SequenceFile related
APIs. The tests all passed when the spark version was specified as 1.0.2. But
this one failed after I changed the spark version to 1.1.0 the new release,
nothing else changed. In addition, it failed when I called rdd2.collect(),
take(1), and first(). But it worked fine when calling rdd2.count(). As you can
see, count() does not need to serialize and ship data while the other three
methods do.
Do you recall any difference between spark 1.0 and 1.1 that might cause this
problem?
Thanks,
Du
From: Matei Zaharia matei.zaha...@gmail.com
Date: Friday, September 12, 2014 at 9:10 PM
To: Du Li l...@yahoo-inc.com.invalid, user@spark.apache.org
user@spark.apache.org, d...@spark.apache.org d...@spark.apache.org
Subject: Re: NullWritable not serializable
Hi Du,
I don't think NullWritable has ever been serializable, so you must be doing
something differently from your previous program. In this case though, just use
a map() to turn your Writables to serializable types (e.g. null and String).
Matie
On September 12, 2014 at 8:48:36 PM, Du Li (l...@yahoo-inc.com.invalid) wrote:
Hi,
I was trying the following on spark-shell (built with apache master and hadoop
2.4.0). Both calling rdd2.collect and calling rdd3.collect threw
java.io.NotSerializableException: org.apache.hadoop.io.NullWritable.
I got the same problem in similar code of my app which uses the newly released
Spark 1.1.0 under hadoop 2.4.0. Previously it worked fine with spark 1.0.2
under either hadoop 2.40 and 0.23.10.
Anybody knows what caused the problem?
Thanks,
Du
import org.apache.hadoop.io.{NullWritable, Text}
val rdd = sc.textFile(README.md)
val res = rdd.map(x = (NullWritable.get(), new Text(x)))
res.saveAsSequenceFile(./test_data)
val rdd2 = sc.sequenceFile(./test_data, classOf[NullWritable], classOf[Text])
rdd2.collect
val rdd3 = sc.sequenceFile[NullWritable,Text](./test_data)
rdd3.collect
NullWritable not serializable
Hi,
I was trying the following on spark-shell (built with apache master and hadoop
2.4.0). Both calling rdd2.collect and calling rdd3.collect threw
java.io.NotSerializableException: org.apache.hadoop.io.NullWritable.
I got the same problem in similar code of my app which uses the newly released
Spark 1.1.0 under hadoop 2.4.0. Previously it worked fine with spark 1.0.2
under either hadoop 2.40 and 0.23.10.
Anybody knows what caused the problem?
Thanks,
Du
import org.apache.hadoop.io.{NullWritable, Text}
val rdd = sc.textFile(README.md)
val res = rdd.map(x = (NullWritable.get(), new Text(x)))
res.saveAsSequenceFile(./test_data)
val rdd2 = sc.sequenceFile(./test_data, classOf[NullWritable], classOf[Text])
rdd2.collect
val rdd3 = sc.sequenceFile[NullWritable,Text](./test_data)
rdd3.collect
Re: NullWritable not serializable
Hi Du,
I don't think NullWritable has ever been serializable, so you must be doing
something differently from your previous program. In this case though, just use
a map() to turn your Writables to serializable types (e.g. null and String).
Matie
On September 12, 2014 at 8:48:36 PM, Du Li (l...@yahoo-inc.com.invalid) wrote:
Hi,
I was trying the following on spark-shell (built with apache master and hadoop
2.4.0). Both calling rdd2.collect and calling rdd3.collect threw
java.io.NotSerializableException: org.apache.hadoop.io.NullWritable.
I got the same problem in similar code of my app which uses the newly released
Spark 1.1.0 under hadoop 2.4.0. Previously it worked fine with spark 1.0.2
under either hadoop 2.40 and 0.23.10.
Anybody knows what caused the problem?
Thanks,
Du
import org.apache.hadoop.io.{NullWritable, Text}
val rdd = sc.textFile(README.md)
val res = rdd.map(x = (NullWritable.get(), new Text(x)))
res.saveAsSequenceFile(./test_data)
val rdd2 = sc.sequenceFile(./test_data, classOf[NullWritable], classOf[Text])
rdd2.collect
val rdd3 = sc.sequenceFile[NullWritable,Text](./test_data)
rdd3.collect
