[Tkinter-discuss] TclStackFree Error

[Trevor J. Christensen]

> The problem is that you must _n e v e r_ access the tk event loop 
> from more than one thread. The best practice is to always run the 
> mainloop () within the main program thread and, if child threads are 
> really necessary, to use e.g. threading.Condition or Queue.Queue 
> objects to handle the communication between Tkinter and the child 
> thread.
 
> Michael
 
Thank you for your help.  Yes, you are right.  Child threads must not
control Tk and must communicate via share a thread communication
mechanism.  The following is my solution which works very well:
 
import threading, time, socket
from Tkinter import *
EVENT = '<<EVENT>>'
PORT = 12339
ADDR = ('', PORT)
BUFSIZ = 1024
class Monitor(object):
    def __init__(self):
        self.s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        self.s.settimeout(0.0)  # non-blocking
        self.s.bind(ADDR)
        self.run()
    def run(self):
        while True:
            try:
                data, addr = self.s.recvfrom(BUFSIZ)
            except socket.error, msg:
                break
            # I modified Tkinter.py slightly to support the 'data' key
            text.event_generate(EVENT, data=data)
        root.after(500, self.run)  # Reschedule
 
def On_EVENT(*args):
    event = args[0]
    text.insert(END, event.data)
    try:                # Handle Tk vertical scroll bar bug
        v = vbar.get()[1]
    except ValueError:
        v = 0.0
    if not v < 0.95:    # Support user review of history
        text.see(tk.END)
    text.see(END)
 
root = Tk()
#---------------------------------------
text = Text(root)
vbar = Scrollbar(root, orient=VERTICAL)
vbar['command'] = text.yview
text['yscrollcommand'] = vbar.set
#---------------------------------------
text.grid(column=0, row=0, sticky=NSEW)
vbar.grid(column=1, row=0, sticky=NS)
root.columnconfigure(0, weight=1)
root.rowconfigure(0, weight=1)
#---------------------------------------
text.bind(EVENT, On_EVENT)
#---------------------------------------
worker = Monitor()
#---------------------------------------
root.mainloop()

Trevor
 
 
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