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From Vasiliki Kalavri <vasilikikala...@gmail.com>
Subject Re: Inconvenient (unforeseen?) consequences of PR #1683
Date Mon, 29 Feb 2016 11:24:00 GMT
In my opinion, the fat jar solution is easier than having to copy the Gelly
jar to all task managers.
I would be in favor of including flink-gelly in the flink-examples module,
but we can also simply document the current behavior nicely.

-V.

On 29 February 2016 at 12:15, Till Rohrmann <trohrmann@apache.org> wrote:

> Good catch :-) I mean we could also change the behaviour to include
> flink-gelly in the flink-gelly-examples module.
>
> On Mon, Feb 29, 2016 at 12:13 PM, Vasiliki Kalavri <
> vasilikikalavri@gmail.com> wrote:
>
> > Thanks Till! Then, we'd better update the docs, too. Currently both links
> > to examples and cluster execution instructions are broken.
> > I'll create an issue.
> >
> > -V.
> >
> > On 29 February 2016 at 11:54, Till Rohrmann <trohrmann@apache.org>
> wrote:
> >
> > > Hi Vasia,
> > >
> > > that is because you're missing the flink-gelly dependency. If you just
> > > build flink-gelly-examples, then it won't contain flink-gelly because
> it
> > is
> > > not a fat jar. You either have to install flink-gelly on your cluster
> or
> > > package it in the final user jar.
> > >
> > > Cheers,
> > > Till
> > >
> > > On Sat, Feb 27, 2016 at 7:19 PM, Vasiliki Kalavri <
> > > vasilikikalavri@gmail.com
> > > > wrote:
> > >
> > > > Hi squirrels,
> > > >
> > > > sorry I've been slow to respond to this, but I'm now testing RC1 and
> > I'm
> > > a
> > > > bit confused with this change.
> > > >
> > > > So far, the easier way to run a Gelly example on a cluster was to
> > package
> > > > and submit the Gelly jar.
> > > > Now, since the flink-gelly project doesn't contain the examples
> > anymore,
> > > I
> > > > tried running a Gelly example by the packaging flink-gelly-examples
> jar
> > > > (mvn package). However, this gives me a ClassNotFoundException.
> > > > e.g. for SingleSourceShortestPaths, the following:
> > > >
> > > > java.lang.RuntimeException: Could not look up the main(String[])
> method
> > > > from the class
> > org.apache.flink.graph.examples.SingleSourceShortestPaths:
> > > > org/apache/flink/graph/spargel/MessagingFunction
> > > > at
> > > >
> > > >
> > >
> >
> org.apache.flink.client.program.PackagedProgram.hasMainMethod(PackagedProgram.java:478)
> > > > at
> > > >
> > > >
> > >
> >
> org.apache.flink.client.program.PackagedProgram.<init>(PackagedProgram.java:216)
> > > > at
> > org.apache.flink.client.CliFrontend.buildProgram(CliFrontend.java:922)
> > > > at org.apache.flink.client.CliFrontend.run(CliFrontend.java:301)
> > > > at
> > > >
> > >
> >
> org.apache.flink.client.CliFrontend.parseParameters(CliFrontend.java:1189)
> > > > at org.apache.flink.client.CliFrontend.main(CliFrontend.java:1239)
> > > > Caused by: java.lang.NoClassDefFoundError:
> > > > org/apache/flink/graph/spargel/MessagingFunction
> > > > at java.lang.Class.getDeclaredMethods0(Native Method)
> > > > at java.lang.Class.privateGetDeclaredMethods(Class.java:2531)
> > > > at java.lang.Class.getMethod0(Class.java:2774)
> > > > at java.lang.Class.getMethod(Class.java:1663)
> > > > at
> > > >
> > > >
> > >
> >
> org.apache.flink.client.program.PackagedProgram.hasMainMethod(PackagedProgram.java:473)
> > > > ... 5 more
> > > > Caused by: java.lang.ClassNotFoundException:
> > > > org.apache.flink.graph.spargel.MessagingFunction
> > > > at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
> > > > at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
> > > > at java.security.AccessController.doPrivileged(Native Method)
> > > > at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
> > > > at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
> > > > at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
> > > > ... 10 more
> > > >
> > > >
> > > > What am I missing here?
> > > >
> > > > Thanks!
> > > > -Vasia.
> > > >
> > > > On 26 February 2016 at 14:10, Márton Balassi <
> balassi.marton@gmail.com
> > >
> > > > wrote:
> > > >
> > > > > Thanks, +1.
> > > > >
> > > > > On Fri, Feb 26, 2016 at 12:35 PM, Stephan Ewen <sewen@apache.org>
> > > wrote:
> > > > >
> > > > > > Hi!
> > > > > >
> > > > > > I think it is a release blocker.
> > > > > >
> > > > > > That was a change to make it possible to use Flink with SBT
(and
> > make
> > > > it
> > > > > > easier to use it with Maven).
> > > > > > Just had an offline chat with Till, and we suggest the following
> > > > > solution:
> > > > > >
> > > > > > All libraries should be split into two projects:
> > > > > >   - library
> > > > > >   - library-examples
> > > > > >
> > > > > > The "library" project has the core flink dependencies as
> "provided"
> > > > > > The "library-examples" project has both the "library" and the
> core
> > > > flink
> > > > > > dependencies with scope "compile"
> > > > > >
> > > > > > That way the example should run in the IDE out of the cox, and
> > users
> > > > that
> > > > > > reference the libraries will still get the correct packaging
> > (include
> > > > the
> > > > > > library in the user jar, but not additionally the core flink
> jars).
> > > > > >
> > > > > > Greetings,
> > > > > > Stephan
> > > > > >
> > > > > >
> > > > > > On Thu, Feb 25, 2016 at 3:45 PM, Márton Balassi <
> > > > > balassi.marton@gmail.com>
> > > > > > wrote:
> > > > > >
> > > > > > > Issued JIRA ticket 3511 to make it referable in other
> > discussions.
> > > > [1]
> > > > > > >
> > > > > > > [1] https://issues.apache.org/jira/browse/FLINK-3511
> > > > > > >
> > > > > > > On Thu, Feb 25, 2016 at 3:36 PM, Márton Balassi <
> > > > > > balassi.marton@gmail.com>
> > > > > > > wrote:
> > > > > > >
> > > > > > > > Recent changes to the build [1] where many libraries
got
> their
> > > core
> > > > > > > > dependencies (the ones included in the flink-dist
fat jar)
> > moved
> > > to
> > > > > the
> > > > > > > > provided scope.
> > > > > > > >
> > > > > > > > The reasoning was that when submitting to the Flink
cluster
> the
> > > > > > > > application already has these dependencies, while
when a user
> > > > writes
> > > > > a
> > > > > > > > program against these libraries she will include the
core
> > > > > dependencies
> > > > > > > > explicitly anyway.
> > > > > > > >
> > > > > > > > There is one other case of usage however, namely when
someone
> > is
> > > > > trying
> > > > > > > to
> > > > > > > > run an application defined in these libraries depending
on
> the
> > > core
> > > > > > jars.
> > > > > > > > To give an example if you were to run the Gelly
> > > ConnectedComponents
> > > > > > > example
> > > > > > > > [2] from an IDE after importing Flink (or running
with java
> > -jar
> > > > > > without
> > > > > > > > including the flink fat jar in the classpath) you
would
> receive
> > > the
> > > > > > > > following class not found exception as per the current
> master:
> > > > > > > >
> > > > > > > > Exception in thread "main" java.lang.NoClassDefFoundError:
> > > > > > > > org/apache/flink/api/common/ProgramDescription
> > > > > > > > at java.lang.ClassLoader.defineClass1(Native Method)
> > > > > > > > at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
> > > > > > > > at
> > > > > > >
> > > >
> java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
> > > > > > > > at
> java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
> > > > > > > > at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
> > > > > > > > at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
> > > > > > > > at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
> > > > > > > > at java.security.AccessController.doPrivileged(Native
Method)
> > > > > > > > at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
> > > > > > > > at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
> > > > > > > > at
> > sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
> > > > > > > > at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
> > > > > > > > at java.lang.Class.forName0(Native Method)
> > > > > > > > at java.lang.Class.forName(Class.java:264)
> > > > > > > > at
> > > > >
> com.intellij.rt.execution.application.AppMain.main(AppMain.java:122)
> > > > > > > >
> > > > > > > > Where the class missing in runtime is in flink-core,
a
> > transitive
> > > > > > > > dependency of the jars moved to the provided scope.
> > > > > > > >
> > > > > > > > Funny thing is we have tests in place to run our examples,
> but
> > > > those
> > > > > > add
> > > > > > > > test scope dependencies re-adding the missing classes,
so it
> is
> > > > never
> > > > > > > > discovered.
> > > > > > > >
> > > > > > > > I agree with the original purpose of PR #1683, but
also think
> > > that
> > > > > the
> > > > > > > > current state makes for very inconvenient user experience.
> > > > > > > >
> > > > > > > > I would like to open a discussion on how and when
to resolve
> > the
> > > > > issue
> > > > > > > > given the release of 1.0.0.
> > > > > > > >
> > > > > > > > 1. Is it a release blocker?
> > > > > > > > 2. Should the change be reverted or is it sufficient
to have
> > > proper
> > > > > > > > documentation around it? Maybe a maven profile for
explicitly
> > for
> > > > > > > > developing Flink without the provided scope?
> > > > > > > >
> > > > > > > > Note that the issue was originally reported by Gábor
Gévay.
> > > > > > > >
> > > > > > > > [1] https://github.com/apache/flink/pull/1683
> > > > > > > > [2]
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> https://github.com/apache/flink/blob/master/flink-libraries/flink-gelly/src/main/java/org/apache/flink/graph/example/ConnectedComponents.java
> > > > > > > >
> > > > > > > > Best,
> > > > > > > >
> > > > > > > > Marton
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

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