DOC: Profiling with VisualVM.

doc/devel/Benchmarking.md

+# Profiling #
+
+If the server is started with the `run-debug-single` make target, it will expose
+the JMX interface, by default on port 9090.  Using a profiler such as VisualVM,
+one can then connect to the CaosDB server and profile execution times.
+
+## Example settings for VisualVM ##
+
+In the sampler settings, you may want to add these expressions to the blocked
+packages: `org.restlet.**, com.mysql.**`.  Branches on the call tree which are
+entirely inside the blacklist, will become leaves.  Alternatively, specify a
+whitelist, for example with `caosdb.server.database.backend.implementation.**`,
+if you only want to see the time spent for certain MySQL calls.
+
 # Manual Java-side benchmarking #
 
 Benchmarking can be done using the `TransactionBenchmark` class (in package