irsend synchronous or asynchronous?

Lircd is running on a Raspberry Pi with 10 pushbuttons.

When the user presses a button, channelnumbers consisting of one or more 
digits are sent to the TV. When shortly after this event (less than a 
second) a new call is executed, (maybe because of bouncing buttons maybe 
because of unhappy user) the TV ends up with channel numbers that can be 
a combination of channelnumbers, or digits may be lost.


When I see the TV getting channel numbers mixed up, is this happening in 
the TV and can I rule out lircd as the culprit?

This is the code that is used:

     import subprocess

     def irsend(self,key_list):
         arg_list = ["irsend", "SEND_ONCE", remote] + key_list
         rtn = subprocess.call(arg_list)
         if rtn:
             print(' '.join(key_list), ' returned errorcode: ', rtn)




Will control to the main python program return only after all key-codes 
are sent completely?
There is no risc to start a new send while the previous is not finished yet?

Is the irsend daemon maintaining a queue with codes to transmit?

In fact the most important question:

Has the client program some responsibility when sending codes in rapid 
succession?


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