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https://issues.apache.org/jira/browse/VELOCITY-731?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13184179#comment-13184179
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Colin Leroy commented on VELOCITY-731:
--------------------------------------
Hello,
Just a heads up about this: it can slow down velosurf users a lot. For example
if your model.xml defines an entity with a huge ROWSET attribute, like in:
<entity name="CATEGORY">
<attribute name="products" result="rowset/PRODUCT">select PRODUCT.* from
PRODUCT where CAT_ID=<CAT_ID/></attribute>
</entity>
If you then do in a Velocity template:
#set($category = $db.CATEGORY.fetch(1))
#foreach($category.products)
...
#end
##This seems constrained inline like this, but can happen when using macros for
example
#if($category)
...
#end
the #if($category) call ends up doing:
TP-Processor96[1] where
[1] velosurf.model.Attribute.query (Attribute.java:161)
[2] velosurf.context.AttributeReference.iterator (AttributeReference.java:83)
[3] java.util.AbstractCollection.toString (AbstractCollection.java:450)
[4] java.lang.String.valueOf (String.java:2 615)
[5] java.lang.StringBuffer.append (StringBuffer.java:220)
[6] java.util.AbstractMap.toString (AbstractMap.java:598)
[7] org.apache.velocity.runtime.parser.node.ASTReference.evaluate
(ASTReference.java:547)
[8] org.apache.velocity.runtime.parser.node.ASTExpression.evaluate
(ASTExpression.java:62)
[9] org.apache.velocity.runtime.parser.node.ASTIfStatement.render
(ASTIfStatement.java:85)
[10] org.apache.velocity.runtime.parser.node.ASTBlock.render
(ASTBlock.java:72)
[11] org.apache.velocity.runtime.parser.node.ASTIfStatement.render
(ASTIfStatement.java:87)
Setting directive.if.tostring.nullcheck = false changed the number of SQL
requests done by some of our list pages, from 14000 to 1200.
> Velocity 1.6 performance is degraded by introduced toString() calls
> -------------------------------------------------------------------
>
> Key: VELOCITY-731
> URL: https://issues.apache.org/jira/browse/VELOCITY-731
> Project: Velocity
> Issue Type: Bug
> Components: Engine
> Affects Versions: 1.6, 1.6.1, 1.6.2
> Environment: Apache Velocity 1.6.2
> Reporter: Jörgen Rydenius
> Fix For: 1.6.x, 1.7
>
> Attachments: configurable_tostring_nullcheck_patch.txt
>
>
> As part of VELOCITY-531, r686428 introduced frequent calls to toString() just
> to check if toString() != null. If toString() implementations are slightly
> complex, and very frequently executed, these calls will degrade the site
> performance. Are they at all necessary? What kind of object would use null as
> a return value for toString()? Is it possible to remove these toString()
> calls from the velocity code again?
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