[rfc][icedtea-web] More shutdown fixes -- Interrupt applet threads after shutdown, fix NPE

[Adam Domurad]

On 02/13/2013 03:44 PM, Adam Domurad wrote:
> ChangeLog:
>
> 2013-02-13  Adam Domurad  <adomurad at redhat.com>
>
>     Interrupt applet threads that did not finish on normal shutdown. 
> Prevent
>     NPE that can occur from sun.applet.AppletPanel.
>     * netx/net/sourceforge/jnlp/NetxPanel.java
>     (destroyApplet): interrupt applet threads
>     * netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java
>     (getPermissions): avoid potential NPE if code source location is
>     missing
>
>
>
> 1.) The NPE:
>
> I had previously posted a patch for an NPE that only occurred during 
> shutdown, but I had not looked into it too deeply.
>
> Now I see the cause is:
>
> sun.applet.AppletPanel.java:
>
>     private AccessControlContext getAccessControlContext(final URL 
> codebase) {
>
>         PermissionCollection perms = (PermissionCollection)
>             AccessController.doPrivileged(new PrivilegedAction() {
>                     public Object run() {
>                         Policy p = java.security.Policy.getPolicy();
>                         if (p != null) {
> >>>                         return p.getPermissions(new 
> CodeSource(null,         <<<
> (java.security.cert.Certificate[]) null));
>                         } else {
>                             return null;
>                         }
>                     }
>                 });
>
> This occurs in PluginAppletViewer#appletShutdown, when 
> p.sendEvent(AppletPanel.APPLET_QUIT); is used. A null source location 
> must thus be supported as such:
>
> diff --git a/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java 
> b/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java
> --- a/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java
> +++ b/netx/net/sourceforge/jnlp/runtime/JNLPClassLoader.java
> @@ -1144,7 +1144,7 @@ public class JNLPClassLoader extends URL
>              }
>
>              // Class from host X should be allowed to connect to host X
> -            if (cs.getLocation().getHost().length() > 0)
> +            if (cs.getLocation() != null && 
> cs.getLocation().getHost().length() > 0)
>                  result.add(new 
> SocketPermission(cs.getLocation().getHost(),
>                          "connect, accept"));
>
>
> 2.) Threads seem to sometimes leak when icedtea-web is refreshed. In 
> fact, this is the cause of an out-of-memory-error I was seeing a while 
> back. ITW had ~ 1000 threads kicking around because they were not 
> properly disposed of.
>
> This interrupts all remaining threads, after joining with the applets 
> main thread. This will be enough to shut down most threads (and fixed 
> the issue I was seeing with horaoficial). It's hard to think of 
> anything further that can be done, save for lots of interrupts in 
> quick succession. Causing thread death was considered, but it can 
> cause stability problems, I think.
>
>

Looks like we need another method for interrupting threads, this method 
caused some problems in my testing.
I will come back to this, however I would very much like this NPE fix to 
get in, thanks.

-Adam