Protect all uses of the random generator with a lock.
Particles break out of their loop when the main loop exits.
diff --git a/Demo/tkinter/guido/brownian.py b/Demo/tkinter/guido/brownian.py
index ec3dbef..b08a956 100644
--- a/Demo/tkinter/guido/brownian.py
+++ b/Demo/tkinter/guido/brownian.py
@@ -1,4 +1,4 @@
-# An example of a multi-threaded Tkinter program.
+# Brownian motion -- an example of a multi-threaded Tkinter program.
from Tkinter import *
import random
@@ -14,22 +14,35 @@
LAMBDA = 10
FILL = 'red'
+stop = 0 # Set when main loop exits
+
+lock = threading.Lock() # Protects the random generator
+
def particle(canvas):
r = RADIUS
- x = random.gauss(WIDTH/2.0, SIGMA)
- y = random.gauss(HEIGHT/2.0, SIGMA)
+ lock.acquire()
+ try:
+ x = random.gauss(WIDTH/2.0, SIGMA)
+ y = random.gauss(HEIGHT/2.0, SIGMA)
+ finally:
+ lock.release()
p = canvas.create_oval(x-r, y-r, x+r, y+r, fill=FILL)
- while 1:
- dx = random.gauss(0, BUZZ)
- dy = random.gauss(0, BUZZ)
+ while not stop:
+ lock.acquire()
+ try:
+ dx = random.gauss(0, BUZZ)
+ dy = random.gauss(0, BUZZ)
+ dt = random.expovariate(LAMBDA)
+ finally:
+ lock.release()
try:
canvas.move(p, dx, dy)
except TclError:
break
- dt = random.expovariate(LAMBDA)
time.sleep(dt)
def main():
+ global stop
root = Tk()
canvas = Canvas(root, width=WIDTH, height=HEIGHT)
canvas.pack(fill='both', expand=1)
@@ -39,6 +52,9 @@
for i in range(np):
t = threading.Thread(target=particle, args=(canvas,))
t.start()
- root.mainloop()
+ try:
+ root.mainloop()
+ finally:
+ stop = 1
main()