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Struts & Hibernate
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| | | Subject: Is Singleton thread safe? | Subject: Is Singleton thread safe? 2005-04-01 - By Dan Marchant
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On Apr 1, 2005 7:55 AM, jon <jon@(protected)> wrote:
>
> Like any other object shared by many threads, it's only thread safe if you
> synchronize.
>
>
> On Fri, 1 Apr 2005 07:54:04 -0800, Julia Liu wrote
>
> > Hi,
> >
> > Is Singleton thread safe? Why?
> >
> > Thanks
> >
> > Julia Liu
> > __ ____ ____ ____ ____ ____ ____
> Yahoo! Messenger
> > Show us what our next emoticon should look like. Join the fun.
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> --
> Jonathan Petruk
> J. Petruk Consulting Inc.
> E-mail: jon@(protected)
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There is also an issue with double-checked locking when using
singletons that could cause iissues depending on how you initialize
your singleton. Here is more info on the double-check locking :
http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html
But also to Jonathan's point the singleton is only as thread safe as
you make it. So this means using locks or synchronization statements
where needed in your singleton.
Hope this helps.
- Dan
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