Terry J. Reedy <[email protected]> added the comment:
>From 1994 to 2017, _tkinter.c has received a steady flow of multiple revisions
>each year, for 333 total, by maybe 20 people including Guido. This makes it
>one of the more actively maintained files and indicates the opposite of
>indifference and not caring.
I tested event generation from threads on my Win 10 machine. With installed
2.7, with non-thread tcl 8.5, the process hangs as described, after 1 key event
is sent and received. So we should document "don't do that".
With installed 64-bit 3.6 with thread-compiled tcl 8.6, I see something
completely different. The process runs for 5 seconds until the stop call. The
two threads alternate sending key events, which are all received in the main
thread. Ditto for built 32-big debug 3.6 and 3.8.
The only problem is that the first t.join() hangs because of a thread deadlock
bug. t.join() blocks until t.run exits. t.run does not exit until the last
event_generate, with running=False, returns. But that blocks until
dummy_handler runs. Dummy_handler does not run when the main thread is blocked
by t.join.
I fixed this by not generating events when running is False. The revised
program exits properly.
def run(self):
tid = self.ident
while True:
time.sleep(0.02)
c = random.choice(string.ascii_letters)
print(running, "%d: sending '%s'"%(tid,c),file=sys.stderr)
if running:
self.target.event_generate(c)
else:
break
I suppose there is a teeny possibility that 'running' could be flipped between
the test and the call. Can that be prevented with a lock?
Another possibility is for stop() to change conditions so that
'self.target.event_generate(c)' fails with an exception, and change if/else to
for/except. My first try sort of works in IDLE but not the console.
----------
nosy: +serhiy.storchaka, terry.reedy
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<https://bugs.python.org/issue33412>
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