To begin with - your code as posted doesn't compile.
I cleaned-up the code and ran it with three clients connected simultaneously and didn't experience the behaviour that you described.
My environment was:
- Windows 7 64 bit
-
Java 1.8 runtime
- netcat 64 bit client (locally connected - didn't try on different platform)
Try and post the actual code that you are running along with some details of your
test environment.