Python IDLE compatible with multithreading?

Question

It seems that IDLE (part of the standard Python Windows install) will not execute multithreaded programs correctly without nasty hangs or bugout crashes. Does anyone know of a way to fix this?

The following program will always hang in IDLE but complete normally when executed with the Python interpreter directly:

import threading, time

printLock = threading.Lock()

def pl(s):
  printLock.acquire()
  print s
  printLock.release()

class myThread( threading.Thread ):
  def run(self):
    i = 0
    for i in range(0,30):
      pl(i)
      time.sleep(0.1)

t = myThread()
t.start()

while threading.activeCount() > 1:
  time.sleep(1)
  pl( time.time() )

print "all done!"

sample output:

U:\dev\py\multithreadtest>python mt.py
0
1
2
3
4
5
6
7
8
9
1277935368.84
10
11
12
13
14
15
16
17
18
19
1277935369.84
20
21
22
23
24
25
26
27
28
29
1277935370.84
1277935371.84
all done!

output when using IDLE "Run Module" function always hangs indefinitely at around the time the line reading 23 or 24 shows up on my machine.

Answer 1

AFAIK it's a crapshoot when running threaded code in IDLE. IDLE itself is threaded with WxPython and uses the GIL liberally so race conditions & deadlocks are common. Unfortunately, I'm not well versed enough in Threading to offer insight on making this thread-safe, beyond the obvious.