Worker thread Issue|Question

[vimalmistry]

I am using same code given in example for worker thread. I am getting this error. I have 6 core CPU.

Listening to port 9001 from thread 1
Failed to listen to port 9001 from thread 2
Failed to listen to port 9001 from thread 4
Failed to listen to port 9001 from thread 5
Failed to listen to port 9001 from thread 3
Failed to listen to port 9001 from thread 6

So Whats going on here?. It's not listing other port or just child worker of first process?