A VelocityEngine allows for global macros and template caching, both
configurable, of course. Context data is never cached or shared by
the engine, though you can yourself reuse a context across multiple
merges.
On Wed, Jun 27, 2012 at 1:03 PM, Bradley Wagner
<bradley.wag...@hannonhill.com> wrote:
> 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 <nbu...@gmail.com> wrote:
>
>> On Wed, Jun 27, 2012 at 11:04 AM, Bradley Wagner
>> <bradley.wag...@hannonhill.com> 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 <nbu...@gmail.com> wrote:
>> >
>> >> What are the macro settings in your velocity.properties?
>> >>
>> >> On Mon, Jun 25, 2012 at 7:40 PM, Bradley Wagner
>> >> <bradley.wag...@hannonhill.com> 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 <
>> >> > bradley.wag...@hannonhill.com> wrote:
>> >> >
>> >> >> Thanks Will. We'll make sure to just initialize it once.
>> >> >>
>> >> >>
>> >> >> On Thu, Jun 7, 2012 at 3:36 PM, Will Glass-Husain <
>> >> wglasshus...@gmail.com>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 <
>> >> >>> bradley.wag...@hannonhill.com> 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 <
>> >> >>> wglasshus...@gmail.com>
>> >> >>> > 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 <
>> >> >>> > > bradley.wag...@hannonhill.com> 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 <
>> >> >>> > > > bradley.wag...@hannonhill.com> 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 <
>> >> >>> > > > wglasshus...@gmail.com>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 <
>> >> >>> > > > >> bradley.wag...@hannonhill.com> 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: user-unsubscr...@velocity.apache.org
>> >> For additional commands, e-mail: user-h...@velocity.apache.org
>> >>
>> >>
>>
>> ---------------------------------------------------------------------
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>>
>>
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