Apologies if I'm misinterpreting, but I think Antoni's concern is that the
SimpleDateFormat's parse and format methods are not thread-safe. The creation
of the converters and their registration can obviously be accomplished in a
thread-safe manner, but if multiple threads call into parse and/or format at
the same time, this will cause a problem. If that's not what Antoni was
saying...it's still a problem ;-). Shouldn't you code a Converter's convert
method with the same approach to thread-safety as an Action's execute/perform
method? If your Converter maintains a SimpleDateFormat instance field that it
uses to either format or parse, it's not thread safe.
Quoting Rick Reumann <[EMAIL PROTECTED]>:
> On Wednesday, November 6, 2002, 4:05:45 PM, Antoni wrote:
>
> AR> Hi, I don't speak english very very well, so this is a bit
> AR> difficult for me to explain, but I'll try ;-) ....
>
> No problem. Most American's don't speak English very well
> (including myself I'm sure:)
>
> AR> I have'nt looked at the beanutils Converter registration, do you have to
>
> AR> register a class or an instance?
>
> It registers an instance one time in the static block at the top
> of the action:
>
> static {
> DateBeanUtilsConverter dateConverter = new
> DateBeanUtilsConverter();
> dateConverter.setFormatPattern( "MMddyyyy" );
> StringBeanUtilsConverterDate myStringConverter = new
> StringBeanUtilsConverterDate();
> myStringConverter.setFormatPattern( "MMddyyyy" );
> ConvertUtils.register( dateConverter, java.util.Date.class );
> ConvertUtils.register( myStringConverter, String.class );
> }
>
> AR> The problem here is that if there is only one instance of your class, and
>
> AR> setFormatPattern is only called once, then if there are two request that
>
> AR> require the use of your class a the same time, served by different
> threads,
> AR> the parse method in your instance of SimpleDateFormat might be called
> AR> concurrently, so (as it isn't thread save) it might fail.
>
> I'm not sure how this would happen as Eddie have both pointed out
> that the static block will only get called one time regardless of
> how many instances are created (at least on a single JVM I'm
> pretty sure that's the case). (On top of that I'm pretty sure on
> one JVM user's all share one servlet instance unless you maybe use
> that SingleThreadModel which I think hands them out from a pool.
> Moot point though I think if I do the stuff in the static block.
> But I could be wrong).
>
> --
>
> Rick
> mailto:maillist@;reumann.net
>
>
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--
Kris Schneider <mailto:kris@;dotech.com>
D.O.Tech <http://www.dotech.com/>
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