fifo fd issue

[Alex fxmbsw7 Ratchev]

i do like, mkfifo ser ; exec 3<>ser ;
all ok yet ?
awk .. <&3 >&3 &
i did with ser instead fd,3 with same results
then i printf >&3
then i mapfile -u 3 and say -n 1
in the read data, by mapfile or cat, the printf ed comes out, not the awk
processed

what can i do, besides trying not to use fd