receive buffer of socket java.net.DatagramSocket@49cfbdab was set to 20MB, but the OS only allocated 3.36MB

Have you seen this warning in NetBeans??? You need to increase the size of receive buffer.

WARNING: receive buffer of socket java.net.DatagramSocket@49cfbdab was set to 20MB, but the OS only allocated 3.36MB. This might lead to performance problems. Please set your max receive buffer in the OS correctly (e.g. net.core.rmem_max on Linux)

Oct 10, 2012 2:36:08 PM org.jgroups.logging.JDKLogImpl warn

WARNING: receive buffer of socket java.net.MulticastSocket@65ad4b68 was set to 25MB, but the OS only allocated 3.36MB. This might lead to performance problems. Please set your max receive buffer in the OS correctly (e.g. net.core.rmem_max on Linux)

Even though, you can ignore this warning, as suggested by NetBeans it is better to handle it. I am using a MAC OS X. So the changes to max buffer will be done via the Terminal.

The Steps are shown below.

Open Terminal.

supz:~# sudo nvram boot-args="ncl=131072"

supz:~# sudo shutdown -r now

After the restart, enter the following lines shown below.

supz:~# sudo sysctl -w kern.ipc.maxsockbuf=33554432

kern.ipc.maxsockbuf: 8388608 -> 33554432

supz:~# sudo sysctl -w net.inet.udp.recvspace=16777216

net.inet.udp.recvspace: 42080 -> 16777216

For more information, refer: http://lists.apple.com/archives/darwin-kernel/2012/Apr/msg00042.html