<p>I'm working on a large application (300K LOC) that is causing a memory leak in the Sun 1.6 JVM (1.6_05). Profiling the Java shows no leak. Are there any diagnostics available from the JVM that might detect the cause of the leak?<br>
I haven't been able to create a simple, isolated Java test case. Is the only way to figure this out by using a C heap analyzer on the JVM?<br>
The application creates a pool of sockets and does a significant amount of network I/O.</p>

Some profiler like profiler4j can show the managed and the unmanaged memory (live curve). Then you can see if you has a leak and when the leak occur. But you does not find more informations.
After this there are 2 possible solutions:
You can with the live curve isolate the problem and create a simpler test until you have find the cause of the problem.
You search your code for the typical problems like:
Instances of the class Thread that are never start.
Images or Graphics that never are dispose
ODBC Bridge Objects that are never close