Chuck, I know that your knowledge of jvm internals is far superior to mine and maybe I'm just missing a point, but for me the difference is obvious.
The Factory only has a static field. That means that Impl class and impl object can't be released as long as the factory isn't released. But as long as the factory itself isn't linked by an attribute which is inside the impl, the factory class can be released. As soon as the factory class is released nothing references the singleton impl object and it can be released. If its released so is it class, and its classloader which is or helds the webapp classloader. Now without the factory, we have a situation where the classloader can't be released since its referenced by the class object, which is referenced by the impl object, which is again referenced by the class object (as the static variable). With suns jdk 1.5 i actually experienced oome on redeploy with code without any issues mentioned by your article. After we removed singleton dependency it went away. regards Leon On 2/16/07, Caldarale, Charles R <[EMAIL PROTECTED]> wrote:
> From: Leon Rosenberg [mailto:[EMAIL PROTECTED] > Subject: Re: PermGen space [ot] > > public class ASingletonFactory{ > private static ASingletonImpl instance = new ASingletonImpl(); > public static AsingletonImpl getInstance(){ > return instance; > } > } > > public class ASingletonImpl{ > ASingletonImpl(){ > } > ///real code here > } That does not alter the situation in the least, if any other class contains a reference to the factory, since the factory contains a reference to the singleton class. If the factory is accessed via reflection rather than direct reference, then both the factory and singleton can be collected when not in use. The same could be said for the previous version of the example. - Chuck THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers. --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
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