ValueExpressions for SelectItems are evaluated too often for checboxes or
radios with spread layout
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Key: TOMAHAWK-1605
URL: https://issues.apache.org/jira/browse/TOMAHAWK-1605
Project: MyFaces Tomahawk
Issue Type: Bug
Components: selectOneRadio / radio
Affects Versions: 1.1.10, 1.1.9
Environment: Myfaces 1.2.9/ 1.2.10, Richfaces 3.3.3, Facelets, Tomcat
6.0.32
Reporter: Michael Heinen
The method HtmlCheckboxRenderer.renderSingleCheckbox (or
HtmlRadioRenderer.renderRadio) calls for each checkbox
RendererUtils.getSelectItemList(uiSelectMany) two times.
RendererUtils creates a new SelectItemsIterator which evaluates the value
expression again for each checkbox that should be rendered and creates each
time a new List with SelectItems.
It is caused by
- method call getConverter(facesContext, uiSelectMany) which calls
RendererUtils.getSelectItemList(uiSelectMany)
- and few lines later by direct call of
RendererUtils.getSelectItemList(uiSelectMany)
>From a performance point of view this is not optimal. It would be better to
>create the list once during response rendering and cache it somewhere (maybe
>in request scope).
But even worse (and therefore from my pov a bug) is that this repeated
evaluation could result in synchronization problems during the rendering of the
response if the bound SelectItems array or collection is changed.
This could easily happen if the SelectItems are cached in an application scoped
bean.
An IndexOutOfBoundsException will occur during response rendering if an item is
removed by another thread.
This does not happen with "list" or "page" layout because the expression to get
the SelectItems is evaluated once and then stored as a local var.
RendererUtils.internalGetSelectItemList contains already a comment for this:
"TODO: Shall we cache the list in a component attribute?"
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