multithreading - Python Threads. Serial Port. KeyboardInterrupt -

i'm implementing multithreaded program 1 of threads reads serial port. i'm having trouble when trying end program keyboardinterrupt. have main thread , 1 reads serial port. code looks this:

import threading import time  def reader(name, port, run_event):     while run_event.is_set():         port.read(1)         #process data...............  if __name__ == "__main__":     run_event = threading.event()     run_event.set()     port=serial.serial(port=args.serialport,baudrate=921600)     port.flush()     port.flushinput()     t1 = threading.thread(target = timed_output, args = ("reader",port,run_event))      t1.start()      try:         while 1:             time.sleep(.1)     except keyboardinterrupt:         print "bye bye"         run_event.clear()         t1.join()         port.close()         print "threads closed" 

sometimes works fine other times not. of logs.

why 1 not caught try-except block?

^ctraceback (most recent call last):   file "bbbdaq.py", line 147, in <module>     time.sleep(0.1) keyboardinterrupt 

two interrupts first 1 takes out of try-expect block , while executing print statement?

^ctraceback (most recent call last):   file "bbbdaq.py", line 149, in <module>     print 'bye bye' keyboardinterrupt 

at point confused. can explain happens there , missing.

-----------edit_1----------------

ive changed try-except block this:

   def signal_handler(signal, frame):             print 'bye bye'             run_event.clear()             t1.join()             port.close()             sys.exit(0)      signal.signal(signal.sigint,signal_handler)      while 1:             time.sleep(0.1) 

most of times program exits expected when ctrl-c hit, other times im getting log:

^cbye bye bye bye exception systemexit: 0 in <module 'threading' '/usr/lib/python2.7/threading.pyc'> ignored 

is exception fired twice, how posible?