Re: Inconsistent and strange NPE when initializing Velocity

Hi Bradley,

Are you initializing Velocity multiple times?

Though I haven't heard of this issue before, it sounds like a race
condition, perhaps if the initialization is called twice at the same time.

WILL

On Wed, Jun 6, 2012 at 8:37 AM, Bradley Wagner <
[email protected]> wrote:

> Hi,
>
> I sent this message before I had subscribed to the list so I wasn't sure if
> the original made it. My apologies if this is a duplicate.
>
> One of our clients running our software is *occasionally* running into the
> stack trace at the bottom when Velocity is initialized. A restart tends to
> fix this problem. But it pops back up after running the system for a while.
>
> They're running:
>
>   - Velocity 1.7
>   - Tomcat 6.0.35
>   - Using the 3.2 of the Apache Commons Collections library
>   - Running Java 1.6.0_31 in Mac OS X 10.6.8
>
> Unfortunately we don't have the ability to debug this problem remotely, so
> we can't see exactly what's going on, but having looked a bit at the
> Extended Properties class, it doesn't seem like it should be possible to
> get an NPE at that line, because of the containsKey() check a few lines
> before.
>
> java.lang.NullPointerException
> at
> org.apache.commons.collections.ExtendedProperties.clearProperty(ExtendedProperties.java:797)
> at
> org.apache.commons.collections.ExtendedProperties.setProperty(ExtendedProperties.java:722)
> at
> org.apache.commons.collections.ExtendedProperties.combine(ExtendedProperties.java:783)
> at
> org.apache.velocity.runtime.RuntimeInstance.setProperties(RuntimeInstance.java:657)
> at
> org.apache.velocity.runtime.RuntimeInstance.init(RuntimeInstance.java:645)
> at
> org.apache.velocity.runtime.RuntimeSingleton.init(RuntimeSingleton.java:226)
> at org.apache.velocity.app.Velocity.init(Velocity.java:97)
> at
> com.hannonhill.cascade.velocity.VelocityEngineUtil.generateMessage(VelocityEngineUtil.java:66)
>
> Also, here's the code that's calling the Velocity.init:
>
>        Properties velocityProps = VelocityProperties.getProperties();
>
>        Velocity.init(velocityProps);
>
> Velocity Properties are just loading the following file contents into a
> properties object:
>
>
> #----------------------------------------------------------------------------
> # This controls if Runtime.error(), info() and warn() messages include the
> # whole stack trace. The last property controls whether invalid references
> # are logged.
>
> #----------------------------------------------------------------------------
> runtime.log.error.stacktrace = false
> runtime.log.warn.stacktrace = false
> runtime.log.info.stacktrace = false
> runtime.log.invalid.reference = true
>
> #----------------------------------------------------------------------------
> # Configuration for the Log4JLogSystem.
> # You must define the runtime.log.logsystem.class property to be:
> #   org.apache.velocity.runtime.log.Log4JLogSystem
> #
> # You must also include Log4J's .jar files into your classpath. They are
> # included with the Velocity distribution in the build/lib directory.
> #
> # There are several different options that you can configure.
> # Uncomment the ones that you want and also define their settings.
>
> #----------------------------------------------------------------------------
>
> #----------------------------------------------------------------------------
> # T E M P L A T E  E N C O D I N G
>
> #----------------------------------------------------------------------------
> input.encoding=UTF-8
> output.encoding=UTF-8
>
> #----------------------------------------------------------------------------
> # F O R E A C H  P R O P E R T I E S
>
> #----------------------------------------------------------------------------
> # These properties control how the counter is accessed in the #foreach
> # directive. By default the reference $velocityCount will be available
> # in the body of the #foreach directive. The default starting value
> # for this reference is 1.
>
> #----------------------------------------------------------------------------
> directive.foreach.counter.name = velocityCount
> directive.foreach.counter.initial.value = 1
>
> #----------------------------------------------------------------------------
> # T E M P L A T E  L O A D E R S
>
> #----------------------------------------------------------------------------
> resource.loader = class
> class.resource.loader.description = Velocity Classpath Resource Loader
> class.resource.loader.class =
> org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader
>