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From "Tony Wu" <wuyue...@gmail.com>
Subject Re: [Approval] Commit Harmony-5460
Date Tue, 19 Feb 2008 13:48:34 GMT
On 2/19/08, Alexei Zakharov <alexei.zakharov@gmail.com> wrote:
> Right. So my solution is to add a synchronization to all accessors of
> this instance variable. Your solution is to create a new object. I
> agree that your solution is probably better because it is faster. The
> only point I do not completely agree with you is your statement that
>
> > Actually your proposal doesn't work
>
> :) Because IMO it works too.

Sorry for my abruptness :)

>
> I'm +1 for your patch to be committed.

That's great. Thanks.

>
> Thanks,
> Alexei
>
> 2008/2/19, Tony Wu <wuyuehao@gmail.com>:
> > On 2/19/08, Alexei Zakharov <alexei.zakharov@gmail.com> wrote:
> > > Tony,
> > >
> > > I'm not sure I understand you completely. I didn't find any places in
> > > the spec that require creation of  a new MessageFormat  instance.
> > The caching makes it possible to share an instance of MessageFormat
> > between several threads, which may cause the synchronization problem
> > because the internal status is inconsistence when do formating. The
> > instance variable used during formating operation may be modified by
> > other thread. To solve this problem we have two choices, one is to
> > make the formating operation be synchronized, another is to create new
> > instance every time.
> >
> > > However, at the same by looking at the code I see that such
> > > implementation of caching is inefficient by itself because
> > > format.toPattern() has the same (or even greater) level of complexity
> > > if compared with MessageFormat's constructor. So I tend to agree that
> > > creation of a new instance makes sense here.
> >
> > yes, it's not efficient.
> > >
> > > Alexei
> > >
> > > 2008/2/19, Tony Wu <wuyuehao@gmail.com>:
> > > > Hi, Alexei
> > > > Actually your proposal doesn't work, the problem is that we can not
> > > > caching a format instance here rather than the caching mechanism. Each
> > > > call to this static method must create a new instance of MessageFormat
> > > > (which has been done by ICU already) then do the formating in order to
> > > > sync the access to instance variable otherwise we need synchronize the
> > > > format method itself. Obviously creating a new instance has higher
> > > > performance.
> > > >
> > > > On 2/19/08, Alexei Zakharov <alexei.zakharov@gmail.com> wrote:
> > > > > Hi Tony,
> > > > >
> > > > > Don't you think that placing a synchronized block around the existing
> > > > > code would be a more transparent fix rather than simply redirecting
> > > > > all job to ICU? I mean something like this:
> > > > >
> > > > > Index: src/main/java/java/text/MessageFormat.java
> > > > > ===================================================================
> > > > > --- src/main/java/java/text/MessageFormat.java  (revision 628711)
> > > > > +++ src/main/java/java/text/MessageFormat.java  (working copy)
> > > > > @@ -446,6 +446,8 @@
> > > > >      *                when the pattern cannot be parsed
> > > > >      */
> > > > >     public static String format(String template, Object... objects)
{
> > > > > +        String result;
> > > > > +
> > > > >         if (objects != null) {
> > > > >             for (int i = 0; i < objects.length; i++) {
> > > > >                 if (objects[i] == null) {
> > > > > @@ -453,12 +455,16 @@
> > > > >                 }
> > > > >             }
> > > > >         }
> > > > > -        if (format == null) {
> > > > > -            format = new com.ibm.icu.text.MessageFormat(template);
> > > > > -        } else if (!template.equals(format.toPattern())){
> > > > > -            format.applyPattern(template);
> > > > > +        synchronized (MessageFormat.class) {
> > > > > +            if (format == null) {
> > > > > +                format = new com.ibm.icu.text.MessageFormat(template);
> > > > > +            } else if (!template.equals(format.toPattern())){
> > > > > +                format.applyPattern(template);
> > > > > +            }
> > > > > +            result = format.format(objects);
> > > > >         }
> > > > > -        return format.format(objects);
> > > > > +
> > > > > +        return result;
> > > > >     }
> > > > >
> > > > >     /**
> > > > >
> > > > >
> > > > > Thanks,
> > > > > Alexei
> > > > >
> > > > > 2008/2/19, Tony Wu <wuyuehao@gmail.com>:
> > > > > > This is a major problem which blocks MessageFormat running on
> > > > > > multi-thread platform. It fails because the caching in Harmony
does
> > > > > > not work with ICU4j 3.8.1. I suggest to commit this patch for
M5.
> > > > > >
> > > > > > --
> > > > > > Tony Wu
> > > > > > China Software Development Lab, IBM
> > > > > >
> > > > >
> > > >
> > > >
> > > > --
> > > > Tony Wu
> > > > China Software Development Lab, IBM
> > > >
> > >
> >
> >
> > --
> > Tony Wu
> > China Software Development Lab, IBM
> >
>


-- 
Tony Wu
China Software Development Lab, IBM

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