[ ~/tmp ] $ perl pg_filevent 
Start to listen ...
Entered numbers()
about to send 1
Connection established
about to send 2
about to send 3
about to send 4
about to send 5
about to send 6
about to send 7
about to send 8
about to send 9
about to send 10
numbers() thread quiting ...
callback triggered
callback triggered
callback triggered