test app can only run once

[yahoo2016]

The "ydlidar_test" can only run once, restart will generate errors in a loop:

Could not lock serial port for exclusive access
Error: [CYdLidar] Error, cannot bind to the specified serial port /dev/ttyUSB0
Warning: Failed to get Lidar Data
check_group_uucp(): mktemp malformed string - should not happencheck_lock_status: No permission to create lock file.
please see: How can I use Lock Files with rxtx? in INSTALL
fhs_lock() lockstatus fail
Could not lock serial port for exclusive access
Error: [CYdLidar] Error, cannot bind to the specified serial port /dev/ttyUSB0
Warning: Failed to get Lidar Data
check_group_uucp(): mktemp malformed string - should not happencheck_lock_status: No permission to create lock file.
please see: How can I use Lock Files with rxtx? in INSTALL
fhs_lock() lockstatus fail
Could not lock serial port for exclusive access
Error: [CYdLidar] Error, cannot bind to the specified serial port /dev/ttyUSB0