separate the singleton itself and the factory.
in the previous example:
public class ASingletonFactory{
private static ASingletonImpl instance = new ASingletonImpl();
public static AsingletonImpl getInstance(){
return instance;
}
}
public class ASingletonImpl{
ASingletonImpl(){
}
///real code here
}
regards
Leon
On 2/16/07, Jason Pyeron <[EMAIL PROTECTED]> wrote:
So how should one write their singleton?
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-----Original Message-----
From: Leon Rosenberg [mailto:[EMAIL PROTECTED]
Sent: Friday, February 16, 2007 11:33
To: Tomcat Users List
Subject: Re: PermGen space
something like this:
public class ASingletonImpl{
private static ASingletonImpl instance;
public synchronized AsingletonImpl getInstance(){
if (instance==null){
instance = new ASingletonImpl();
}
return instance;
}
///real code here
}
The problem is the cyclic dependence between the Class object, the
ASingletonImpl object and the according ClassLoader. This way nothing
can be freed by the gc.
regards
Leon
On 2/16/07, Jiang, Peiyun <[EMAIL PROTECTED]> wrote:
> Just curious, can you elaborate on badly programmed singletons?
>
> Thanks.
>
> Peiyun
>
> -----Original Message-----
> From: Leon Rosenberg [mailto:[EMAIL PROTECTED]
> Sent: February 16, 2007 11:08 AM
> To: Tomcat Users List
> Subject: Re: PermGen space
>
>
> The typical problem here are badly programmed singletons. Do you have any?
>
> regards
> Leon
>
> On 2/16/07, Davide Romanini <[EMAIL PROTECTED]> wrote:
> > I'm too have this problem, it arises because for some reason the Tomcat
> > WebAppClassloader cannot be garbage collected after undeploy. I made a
> > lot of tests and didn't find any solution, also very simple and small
> > webapps, when loaded/unloaded frequently, caused the problem... :-(
> >
>
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