Trouble with Timer implementation on server-side

Hey folks

I am having a weird problem when I try to use a Timer on the server-
side code of my gwt app.

After I import the package:

import  java.util.Timer;

and declare  my variable:

    public Timer refreshTimer;

IF I do this:

refreshTimer = new Timer();

I get these errors:


30-Jul-2009 21:36:57
com.google.appengine.tools.development.ApiProxyLocalImpl log
SEVERE: [1248989817022000] javax.servlet.ServletContext log: Exception
while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method
'public abstract java.util.ArrayList
com.google.gwt.spacefighter.client.SpaceFighterService.startup
(com.google.gwt.spacefighter.client.Phantom)' threw an unexpected
exception: java.security.AccessControlException: access denied
(java.lang.RuntimePermission modifyThreadGroup)
        at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure
(RPC.java:360)
        at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse
(RPC.java:546)
        at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall
(RemoteServiceServlet.java:166)
        at com.google.gwt.user.server.rpc.RemoteServiceServlet.doPost
(RemoteServiceServlet.java:86)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:713)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:806)
        at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:
487)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter
(ServletHandler.java:1093)
        at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter
(TransactionCleanupFilter.java:43)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter
(ServletHandler.java:1084)
        at com.google.appengine.tools.development.StaticFileFilter.doFilter
(StaticFileFilter.java:124)
        at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter
(ServletHandler.java:1084)
        at org.mortbay.jetty.servlet.ServletHandler.handle
(ServletHandler.java:360)
        at org.mortbay.jetty.security.SecurityHandler.handle
(SecurityHandler.java:216)
        at org.mortbay.jetty.servlet.SessionHandler.handle
(SessionHandler.java:181)
        at org.mortbay.jetty.handler.ContextHandler.handle
(ContextHandler.java:712)
        at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:
405)
        at com.google.apphosting.utils.jetty.DevAppEngineWebAppContext.handle
(DevAppEngineWebAppContext.java:54)
        at org.mortbay.jetty.handler.HandlerWrapper.handle
(HandlerWrapper.java:139)
        at com.google.appengine.tools.development.JettyContainerService
$ApiProxyHandler.handle(JettyContainerService.java:313)
        at org.mortbay.jetty.handler.HandlerWrapper.handle
(HandlerWrapper.java:139)
        at org.mortbay.jetty.Server.handle(Server.java:313)
        at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:
506)
        at org.mortbay.jetty.HttpConnection$RequestHandler.content
(HttpConnection.java:844)
        at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:644)
        at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:205)
        at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:381)
        at org.mortbay.io.nio.SelectChannelEndPoint.run
(SelectChannelEndPoint.java:396)
        at org.mortbay.thread.BoundedThreadPool$PoolThread.run
(BoundedThreadPool.java:442)
Caused by: java.security.AccessControlException: access denied
(java.lang.RuntimePermission modifyThreadGroup)
        at java.security.AccessControlContext.checkPermission(Unknown Source)
        at java.security.AccessController.checkPermission(Unknown Source)
        at java.lang.SecurityManager.checkPermission(Unknown Source)
        at com.google.appengine.tools.development.DevAppServerFactory
$CustomSecurityManager.checkPermission(DevAppServerFactory.java:128)
        at com.google.appengine.tools.development.DevAppServerFactory
$CustomSecurityManager.checkAccess(DevAppServerFactory.java:155)
        at java.lang.ThreadGroup.checkAccess(Unknown Source)
        at java.lang.Thread.init(Unknown Source)
        at java.lang.Thread.<init>(Unknown Source)
        at java.util.TimerThread.<init>(Unknown Source)
        at java.util.Timer.<init>(Unknown Source)
        at java.util.Timer.<init>(Unknown Source)
        at com.google.gwt.spacefighter.server.SpaceFighterServiceImpl.startup
(SpaceFighterServiceImpl.java:46)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse
(RPC.java:527)
        ... 27 more


If I comment the line that creates the timer all of those go away.

It seems to me like the Timer creation somehow violates security and
does not allow the server to communicate with the client through RPC.
Someone can help me to figure out the problem and solve it ?

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