gpsd stop when other process read gps device file

Question

I have a Ubuntu computer with GPS device attachted at /dev/ttyUSB3 and gpsd is running fine. When i try to read /dev/ttyUSB3 from other process (e.g. cat /dev/ttyUSB3), gpsd does not work anymore. I have been try to start gpsd width debug option and got following error messages:

gpsd: INFO: closing GPS=/dev/ttyUSB3 (6)
gpsd: ERROR: select: Bad file descriptor

My gpsd version is: 3.11~dev

Can anyone tell me, why?
Thanks in advance.

Answer 1

Resolved.

When there are two processes read from the same tty device, they can interfere each other. (http://www.tldp.org/LDP/nag2/x-087-2-serial.devices.html)