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https://issues.apache.org/jira/browse/SPARK-1520?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13989206#comment-13989206
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Xiangrui Meng commented on SPARK-1520:
--------------------------------------
Koert, which JDK6 did you use? This problem was fixed in a later version of
openjdk-6. If you are using openjdk-6, you can try upgrading it to the latest
version and see whether the problem still exists.
> Assembly Jar with more than 65536 files won't work when compiled on JDK7 and
> run on JDK6
> -----------------------------------------------------------------------------------------
>
> Key: SPARK-1520
> URL: https://issues.apache.org/jira/browse/SPARK-1520
> Project: Spark
> Issue Type: Bug
> Components: MLlib, Spark Core
> Reporter: Patrick Wendell
> Assignee: Xiangrui Meng
> Priority: Blocker
> Fix For: 1.0.0
>
>
> This is a real doozie - when compiling a Spark assembly with JDK7, the
> produced jar does not work well with JRE6. I confirmed the byte code being
> produced is JDK 6 compatible (major version 50). What happens is that,
> silently, the JRE will not load any class files from the assembled jar.
> {code}
> $> sbt/sbt assembly/assembly
> $> /usr/lib/jvm/java-1.7.0-openjdk-amd64/bin/java -cp
> /home/patrick/Documents/spark/assembly/target/scala-2.10/spark-assembly-1.0.0-SNAPSHOT-hadoop1.0.4.jar
> org.apache.spark.ui.UIWorkloadGenerator
> usage: ./bin/spark-class org.apache.spark.ui.UIWorkloadGenerator [master]
> [FIFO|FAIR]
> $> /usr/lib/jvm/java-1.6.0-openjdk-amd64/bin/java -cp
> /home/patrick/Documents/spark/assembly/target/scala-2.10/spark-assembly-1.0.0-SNAPSHOT-hadoop1.0.4.jar
> org.apache.spark.ui.UIWorkloadGenerator
> Exception in thread "main" java.lang.NoClassDefFoundError:
> org/apache/spark/ui/UIWorkloadGenerator
> Caused by: java.lang.ClassNotFoundException:
> org.apache.spark.ui.UIWorkloadGenerator
> at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
> at java.security.AccessController.doPrivileged(Native Method)
> at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
> at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
> Could not find the main class: org.apache.spark.ui.UIWorkloadGenerator.
> Program will exit.
> {code}
> I also noticed that if the jar is unzipped, and the classpath set to the
> currently directory, it "just works". Finally, if the assembly jar is
> compiled with JDK6, it also works. The error is seen with any class, not just
> the UIWorkloadGenerator. Also, this error doesn't exist in branch 0.9, only
> in master.
> h1. Isolation and Cause
> The package-time behavior of Java 6 and 7 differ with respect to the format
> used for jar files:
> ||Number of entries||JDK 6||JDK 7||
> |<= 65536|zip|zip|
> |> 65536|zip*|zip64|
> zip* is a workaround for the original zip format that [described in
> JDK-6828461|https://bugs.openjdk.java.net/browse/JDK-4828461] that allows
> some versions of Java 6 to support larger assembly jars.
> The Scala libraries we depend on have added a large number of classes which
> bumped us over the limit. This causes the Java 7 packaging to not work with
> Java 6. We can probably go back under the limit by clearing out some
> accidental inclusion of FastUtil, but eventually we'll go over again.
> The real answer is to force people to build with JDK 6 if they want to run
> Spark on JRE 6.
> -I've found that if I just unpack and re-pack the jar (using `jar`) it always
> works:-
> {code}
> $ cd assembly/target/scala-2.10/
> $ /usr/lib/jvm/java-1.6.0-openjdk-amd64/bin/java -cp
> ./spark-assembly-1.0.0-SNAPSHOT-hadoop1.0.4.jar
> org.apache.spark.ui.UIWorkloadGenerator # fails
> $ jar xvf spark-assembly-1.0.0-SNAPSHOT-hadoop1.0.4.jar
> $ jar cvf spark-assembly-1.0.0-SNAPSHOT-hadoop1.0.4.jar *
> $ /usr/lib/jvm/java-1.6.0-openjdk-amd64/bin/java -cp
> ./spark-assembly-1.0.0-SNAPSHOT-hadoop1.0.4.jar
> org.apache.spark.ui.UIWorkloadGenerator # succeeds
> {code}
> -I also noticed something of note. The Breeze package contains single
> directories that have huge numbers of files in them (e.g. 2000+ class files
> in one directory). It's possible we are hitting some weird bugs/corner cases
> with compatibility of the internal storage format of the jar itself.-
> -I narrowed this down specifically to the inclusion of the breeze library.
> Just adding breeze to an older (unaffected) build triggered the issue.-
> -I ran a git bisection and this appeared after the MLLib sparse vector patch
> was merged:-
> https://github.com/apache/spark/commit/80c29689ae3b589254a571da3ddb5f9c866ae534
> SPARK-1212
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