Description Jürgen Becker 2011-09-26 08:18:44 EDT

The WeakRef starts a new Remover(which extends
Thread). On the client side this is no problem, because the thread is stopped
when the client application is stopped,
On the server side in a webapp container, like Tomcat, the thread is not
stopped, after the application (war) is undeployed.
To verify this, undeploy the webapp and create a thread dump via "jstack <pid>"
and search for WeakRef. Something like this will show up -
even after undeploying the webapp:

"WeakRef remover" daemon prio=10 tid=0x0000000041b82000 nid=0x212a in Object.wait() [0x00007f37be168000]
   java.lang.Thread.State: WAITING (on object monitor)
        at java.lang.Object.wait(Native Method)
        - waiting on <0x00000000fecd5188> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:118)
        - locked <0x00000000fecd5188> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:134)
        at org.eclipse.riena.core.util.WeakRef$Remover.run(WeakRef.java:91)

The running thread can prevent the container from freeing resources, resulting
in memory leaks.