Re: Permissions and threads

• To: Matthew Laurenson <MatthewL@xxxxxxxxxxxxxxxx>
• Subject: Re: Permissions and threads
• From: Dave Glowacki <dglo@xxxxxxxxxxxxxxxxxxxxxx>
• Date: Fri, 16 Jul 1999 13:44:20 -0500

Matthew Laurenson wrote:
> Greetings all,
> 
> I have a small visad application which I am running as an applet, either
> from Netscape with the Java plug-in or using the AppletViewer. The
> applet sits on a web server with visad.jar. When run, it communicates
> via RMI to a server program running on another machine (which in turn
> talks to some weather databases via JDBC).
> 
> The applet uses DisplayImplJ3D to show a map of weather stations, with
> their period of operation in the z-axis.
> 
> I've included the code below in case it is relevant.

Thanks, that really helped with debugging!

> The thing basically works, but with one annoying aspect. I have to grant
> the codebase http:...visad.jar AllPermission to avoid getting the
> following message when I rotate the 3D display:

The following patch to visad/util/ThreadPool.java should fix your problem.
(P.S. thanks for the excellent bug report!)

Index: visad/util/ThreadPool.java
==================================================================
RCS file: /source-control/visad/util/ThreadPool.java,v
retrieving revision 1.3
diff -u -r1.3 ThreadPool.java
--- ThreadPool.java     1999/07/14 21:57:38     1.3
+++ ThreadPool.java     1999/07/16 18:40:41
@@ -164,9 +164,14 @@
         if (threads != null && threads.size() < maxThreads) {
 
           // ...spawn a new thread and tell it to deal with this
-          Thread t = new ThreadMinnow(this);
-          threads.addElement(t);
-          threadLock.notify();
+          try {
+            Thread t = new ThreadMinnow(this);
+            threads.addElement(t);
+            threadLock.notify();
+          } catch (SecurityException e) {
+            // can't spawn a thread from this ThreadGroup...
+            // wait until something's queued from the main thread
+          }
         } else {
 
           // try to wake up all waiting threads to deal with the backlog

• References:
  • Permissions and threads
    • From: Matthew Laurenson