Re: Inconsistent and strange NPE when initializing Velocity

Thanks, Nathan, I'll give that a shot.

Offhand, is there anything else I need to be aware of that could be
persisting across template renders (like velocimacros) since I'm now using
a single instance of engine?

On Wed, Jun 27, 2012 at 3:51 PM, Nathan Bubna <[email protected]> wrote:

> On Wed, Jun 27, 2012 at 11:04 AM, Bradley Wagner
> <[email protected]> wrote:
> > None explicitly specified.
> >
> > I looked at a default velocity properties that's in our project but that
> > we're not using:
> >
> > velocimacro.library = VM_global_library.vm
> > velocimacro.permissions.allow.inline = true
> > velocimacro.permissions.allow.inline.to.replace.global = false
> > velocimacro.permissions.allow.inline.local.scope = false
> > velocimacro.context.localscope = false
> >
> > I'm guessing this has something to do with these things being scoped
> > globally by default or something?
>
> yeah, you should set
>
> velocimacro.permissions.allow.inline.local.scope = true
>
> > On Wed, Jun 27, 2012 at 12:39 PM, Nathan Bubna <[email protected]> wrote:
> >
> >> What are the macro settings in your velocity.properties?
> >>
> >> On Mon, Jun 25, 2012 at 7:40 PM, Bradley Wagner
> >> <[email protected]> wrote:
> >> > We're noticing something now that may or may not be related to our
> change
> >> > to only use a single instance of the Velocity Engine.
> >> >
> >> > Macros that we define in one template seem to be sticking around and
> >> being
> >> > used when we go to merge or evaluate a different template.
> >> >
> >> > Is this possible related and to be expected when using a single
> instance
> >> of
> >> > the VelocityEngine?
> >> >
> >> > On Thu, Jun 7, 2012 at 5:28 PM, Bradley Wagner <
> >> > [email protected]> wrote:
> >> >
> >> >> Thanks Will. We'll make sure to just initialize it once.
> >> >>
> >> >>
> >> >> On Thu, Jun 7, 2012 at 3:36 PM, Will Glass-Husain <
> >> [email protected]>wrote:
> >> >>
> >> >>> Hi,
> >> >>>
> >> >>> You should use either the Velocity static calls or the
> VelocityEngine
> >> but
> >> >>> not both-- it's confusing.  They don't technically interfere with
> each
> >> >>> other, but it'll be simpler and less error prone not to mix.
> >> >>>
> >> >>> It's also a performance hit to continually reinitialize Velocity.
> >>  There's
> >> >>> no need to do this every time you process a page.  Besides the cost
> of
> >> >>> initialization, it also prevents you from doing any caching.
> >> >>>
> >> >>> Here's the general pattern
> >> >>> * On app start up, initialize a VelocityEngine.  Store it somewhere.
> >> >>> * Every time you need to process a template
> >> >>>     --> get the template
> >> >>>     --> create and populate a context
> >> >>>     --> using the velocity engine, merge the template (with the
> >> context)
> >> >>>
> >> >>> WILL
> >> >>>
> >> >>>
> >> >>> On Thu, Jun 7, 2012 at 8:26 AM, Bradley Wagner <
> >> >>> [email protected]> wrote:
> >> >>>
> >> >>> > Thanks Will.
> >> >>> >
> >> >>> > So looking over the developer documentation about initialization
> and
> >> our
> >> >>> > code, it looks like we're using a mix of the Singleton Velocity
> >> Engine
> >> >>> and
> >> >>> > Separate Instances in certain cases. However, in all these cases,
> >> we're
> >> >>> > using the same set of properties. The documentation suggests that
> the
> >> >>> > Separate Instance method is the newer way to do it, but you're
> saying
> >> >>> that
> >> >>> > if we can get away with initializing Velocity one using
> >> Velocity.init()
> >> >>> we
> >> >>> > should do that for better performance, yes? Are both mechanisms
> for
> >> >>> > evaluating templates thread-safe?
> >> >>> >
> >> >>> > In one place we're doing:
> >> >>> >
> >> >>> > VelocityContext context = new VelocityContext(contextMap)
> >> >>> > Properties props = VelocityProperties.getProperties();
> >> >>> > Velocity.init(props);
> >> >>> > String templatePath =
> >> VelocityTemplates.getTemplatePath(templateName);
> >> >>> > Template template = Velocity.getTemplate(templatePath);
> >> >>> > StringWriter writer = new StringWriter();
> >> >>> > template.merge(context, writer);
> >> >>> > return writer.toString();
> >> >>> >
> >> >>> > and in another we're doing:
> >> >>> >
> >> >>> > VelocityEngine engine = new VelocityEngine();
> >> >>> > Properties velocityProps = VelocityProperties.getProperties();
> >> >>> > engine.init(velocityProps);
> >> >>> >
> >> >>> > // Get a template as stream.
> >> >>> > StringWriter writer = new StringWriter();
> >> >>> > StringReader reader = new StringReader(template);
> >> >>> > // create a temporary template name
> >> >>> > String tempTemplateName = "velocityTransform-" +
> >> >>> > System.currentTimeMillis();
> >> >>> >
> >> >>> > // ask Velocity to evaluate it.
> >> >>> > boolean result = engine.evaluate(context, writer,
> tempTemplateName,
> >> >>> > reader);
> >> >>> >
> >> >>> > String strResult = null;
> >> >>> > if (result)
> >> >>> > {
> >> >>> >    strResult = writer.getBuffer().toString();
> >> >>> > }
> >> >>> > return strResult;
> >> >>> >
> >> >>> > Thanks a bunch for your help!
> >> >>> >
> >> >>> > On Wed, Jun 6, 2012 at 6:34 PM, Will Glass-Husain <
> >> >>> [email protected]>
> >> >>> > wrote:
> >> >>> > >
> >> >>> > > You only need to initialize Velocity once.  Performance is much
> >> better
> >> >>> > that
> >> >>> > > way.
> >> >>> > >
> >> >>> > > WILL
> >> >>> > >
> >> >>> > > On Wed, Jun 6, 2012 at 2:37 PM, Bradley Wagner <
> >> >>> > > [email protected]> wrote:
> >> >>> > >
> >> >>> > > > The odd part about that is that while I could see this being a
> >> race
> >> >>> > > > condition... once Velocity gets into this state it doesn't
> matter
> >> >>> how
> >> >>> > many
> >> >>> > > > times we call Velocity.init, it returns the NPE every time. I
> >> guess
> >> >>> I
> >> >>> > > > should have mentioned that in the original post. Basically
> once
> >> it
> >> >>> > starts
> >> >>> > > > returning NPE our only recourse is to restart Tomcat, which
> fixes
> >> >>> the
> >> >>> > > > problem, until  it pops up again.
> >> >>> > > >
> >> >>> > > > On Wed, Jun 6, 2012 at 5:35 PM, Bradley Wagner <
> >> >>> > > > [email protected]> wrote:
> >> >>> > > >
> >> >>> > > > > Ha, that's a good question. Yes, we're initializing Velocity
> >> LOTS
> >> >>> of
> >> >>> > > > > times. Basically every time we use it to create these
> messages
> >> in
> >> >>> our
> >> >>> > > > > message util. I'm guessing that's not recommended?
> >> >>> > > > >
> >> >>> > > > >
> >> >>> > > > > On Wed, Jun 6, 2012 at 1:53 PM, Will Glass-Husain <
> >> >>> > > > [email protected]>wrote:
> >> >>> > > > >
> >> >>> > > > >> 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
> >> >>> > > > >> >
> >> >>> > > > >>
> >> >>> > > > >
> >> >>> > > > >
> >> >>> > > >
> >> >>> >
> >> >>>
> >> >>
> >> >>
> >>
> >> ---------------------------------------------------------------------
> >> To unsubscribe, e-mail: [email protected]
> >> For additional commands, e-mail: [email protected]
> >>
> >>
>
> ---------------------------------------------------------------------
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