[ovirt-devel] How to debug NullPointerException for project restapi-def inition of version 3.6.4.1?

[Juan Hernández]

On 04/07/2016 08:34 AM, Martin Mucha wrote:
> 
> 
> ----- Original Message -----
>>
>>
>> On Wed, Apr 6, 2016 at 6:03 PM, Juan Hernández < jhernand at redhat.com > wrote:
>>
>>
>>
>> On 04/06/2016 11:51 AM, Kai Kang wrote:
>>> Hi,
>>>
>>> I am building ovirt-engine 3.6.4.1 and failed with NullPointerException.
>>> I build for cross compile with commands:
>>>
>>>
>>>
>>> tmp_repo=/buildarea3/kkang/builds/Mar31-ovrit-engine/bitbake_build/tmp/work/corei7-64-wrs-linux/ovirt-engine/3.6.4.1-r0/repo
>>> export MAVEN_OPTS="-Dmaven.repo.local=$tmp_repo"
>>>
>>> make EXTRA_BUILD_FLAGS="-s
>>> /buildarea3/kkang/builds/Mar31-ovrit-engine/bitbake_build/tmp/work/corei7-64-wrs-linux/ovirt-engine/3.6.4.1-r0/settings.xml
>>> --debug --offline" -j1 BUILD_GWT=1 BUILD_LOCALES=0
>>> BUILD_UT=1 BUILD_VALIDATION=0
>>> JAVA_DIR=/usr/share/ovirt-engine/java LOCALSTATE_DIR=/var
>>> MAVENPOM_DIR=/usr/share/ovirt-engine/maven-poms PREFIX=/usr
>>> SYSCONF_DIR=/etc PKG_SYSCONF_DIR=/etc/ovirt-engine
>>> PKG_DOC_DIR=/usr/doc/ovirt-engine
>>> PKG_EAR_DIR=/usr/share/ovirt-engine/engine.ear
>>> PKG_PKI_DIR=/etc/pki/ovirt-engine
>>> PKG_JBOSS_MODULES=/usr/share/ovirt-engine/modules
>>> PKG_CACHE_DIR=/var/cache/ovirt-engine
>>> PKG_LOG_DIR=/var/log/ovirt-engine
>>> PKG_TMP_DIR=/var/tmp/ovirt-engine
>>> PKG_STATE_DIR=/var/lib/ovirt-engine PKG_USER=ovirt PKG_GROUP=ovirt
>>> all
>>>
>>>
>>> The error messages show:
>>>
>>> [INFO] oVirt Engine API Definition ....................... FAILURE [1.476s]
>>> ...
>>> [INFO]
>>> ------------------------------------------------------------------------
>>> [ERROR] Failed to execute goal
>>> org.codehaus.mojo:exec-maven-plugin:1.2:java (default) on project
>>> restapi-definition: An exception occured while executing the Java class.
>>> null: InvocationTargetException: NullPointerException -> [Help 1]
>>> org.apache.maven.lifecycle.LifecycleExecutionException: Failed to
>>> execute goal org.codehaus.mojo:exec-maven-plugin:1.2:java (default) on
>>> project restapi-definition: An exception occured while executing the
>>> Java class. null
>>> at
>>> org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:216)
>>> ...
>>> at javax.xml.bind.JAXB.marshal(JAXB.java:332)
>>> at
>>> org.ovirt.engine.api.rsdl.RsdlManager.serializeRsdl(RsdlManager.java:134)
>>> at
>>> org.ovirt.engine.api.rsdl.RsdlManager.generateRsdlFile(RsdlManager.java:84)
>>> at org.ovirt.engine.api.rsdl.RsdlManager.main(RsdlManager.java:58)
>>> ... 6 more
>>>
>>>
>>> My questions are:
>>>
>>> 1 I know the error occurs in
>>> file
>>> backend/manager/modules/restapi/interface/definition/src/main/java/org/ovirt/engine/api/rsdl/RsdlManager.java,
>>> but how to debug it?
>>>
>>> 2 When I remove pom and jar files of javax.xml.bind.JAXB in mave repo
>>> with offline mode, it still could find the class.
>>> Which javax.xml.bind.JAXB is used? I searched the ovirt engine repo but
>>> didn't find it either.
>>>
>>
>> The version of JAXB used by that area of the code is the version of JAXB
>> included in the JDK that you are using for the build. So the question is
>> what version of the JDK are you using?
>>
>> Hi Juan,
>>
>> I am using icedtea7 to build openjdk-7. And I found the JAXB file.
> 
> note: I saw same line using java-1.8.0-openjdk installed from repo. 
> 

The build of the master branch (what will eventually be oVirt 4)
requires Java 8, but Kai Kang is trying to build 3.6.4.1, which should
build correctly with Java 7. I just tried that, with the version of
OpenJDK 7 included in CentOS 7:

  $ java -version
  java version "1.7.0_85"
  OpenJDK Runtime Environment (rhel-2.6.1.2.el7_1-x86_64 u85-b01)
  OpenJDK 64-Bit Server VM (build 24.85-b03, mixed mode

Kai Kang, from the "icedtea7" and "openjdk-7" names I assume that you
aren't using CentOS or Fedora, which are the typical distributions used
for oVirt. What distribution are you using exactly? And what version of
openjdk-7 exactly? If you share that information we may be able to
reproduce.

>>
>> Would you like to give some advice how to debug this issue? Does jdb could
>> debug such code?
>>

The easiest way to debug this to have an IDE, like IntelliJ Idea, or
Eclipse, set a breakpoint in the relevant line and then debug the Maven
build.

You may be able to debug the Maven build with "jdb" as well, but I can't
help you with that, I'm not familiar with it.

I'd suggest to perform the build of the relevant component only, using
the Maven -X option. For example:

1. Do a complete build of the engine, manually:

  $ mvn clean install -DskipTests

This should fail in the same point where it failed previously, as you
will be using the same JDK.

2. Change to the directory of the failing component, and repeat the
build, with the "-X" flag:

  $ cd backend/manager/modules/restapi/interface/definition
  $ mvn clean install -X -DskipTests > build.log

That should fail again, but there will be more information in the
"build.log" file. Inspect and maybe share it with us.

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