Stavros Kontopoulos created SPARK-22657:
-------------------------------------------
Summary: Hadoop fs implementation classes are not loaded if they
are part of the app jar or other jar when --packages flag is used
Key: SPARK-22657
URL: https://issues.apache.org/jira/browse/SPARK-22657
Project: Spark
Issue Type: Bug
Components: Spark Core
Affects Versions: 2.3.0
Reporter: Stavros Kontopoulos
Reproduce run:
./bin/spark-submit --master mesos://leader.mesos:5050 \
--packages com.github.scopt:scopt_2.11:3.5.0 \
--conf spark.cores.max=8 \
--conf
spark.mesos.executor.docker.image=mesosphere/spark:beta-2.1.1-2.2.0-2-hadoop-2.6
\
--conf spark.mesos.executor.docker.forcePullImage=true \
--class S3Job
http://s3-us-west-2.amazonaws.com/arand-sandbox-mesosphere/dcos-spark-scala-tests-assembly-0.1-SNAPSHOT.jar
\
--readUrl s3n://arand-sandbox-mesosphere/big.txt --writeUrl
s3n://arand-sandbox-mesosphere/linecount.out
within a container created with mesosphere/spark:beta-2.1.1-2.2.0-2-hadoop-2.6
You get: "Exception in thread "main" java.io.IOException: No FileSystem for
scheme: s3n"
This can be run reproduced with local[*] as well.
The specific spark job used is[[
https://github.com/mesosphere/spark-build/blob/d5c50e9ae3b1438e0c4ba96ff9f36d5dafb6a466/tests/jobs/scala/src/main/scala/S3Job.scala
| here ]].
Using this code :
https://gist.github.com/fdp-ci/564befd7747bc037bd6c7415e8d2e0df
You get: https://gist.github.com/fdp-ci/21ae1c415306200a877ee0b4ef805fc5
The commit that introduced this is:
5800144a54f5c0180ccf67392f32c3e8a51119b1[m -[33m[m [SPARK-21012][SUBMIT] Add
glob support for resources adding to Spark [32m(5 months ago)
[1;34m<jerryshao>[m Thu, 6 Jul 2017 15:32:49 +0800
https://github.com/apache/spark/pull/18235/files check line 950
The Filesystem class is initialized already before the main of the spark job is
launched... the reason is --packages logic uses hadoop libraries to download
files....
Maven resolution happens before the app jar and the resolved jars are added to
the classpath. So at that moment there is no s3n to add to the static map when
the Filesystem static members are first initialized and also filled
(SERVICE_FILE_SYSTEMS).
Later in the spark job main where we try to access the s3n filesystem we get
the exception (at this point the app jar has the s3n implementation in it and
its on the class path but that scheme is not loaded in the static map of the
Filesystem class)...
hadoopConf.set("fs.s3n.impl.disable.cache", "true") has no effect since the
problem is with the static map which is filled once and only once.
That's why we see two prints of the map contents in the output above when
--packages is used. The first print is before creating the s3n filesystem. We
use reflection there to get the static map's entries btw. When --packages is
not used that map is empty since the Filesystem class is not yet loaded by the
classloader.
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