Hello,
Recently I started to use LISTEN and NOTIFY with psycopg2 and I'm
experiencing rare hangs of the application. I suspect my notification
handling logic may be incorrect, in particular, I started to wonder
whether it is OK to share a connection between a thread that listens
for a notification and a thread that sends a notification.
My notification thread executes:
cursor = connection.cursor() # this connection has ISOLATION_LEVEL_AUTOCOMMIT
cursor.execute("NOTIFY " + channel + ", %s", [message])
cursor.close()
My listening thread executes:
cursor = connection.cursor() # This is the same connection that is
used by the NOTIFY thread.
cursor.execute('LISTEN %s;' % (channel))
while True:
if select.select([connection],[],[]) == ([],[],[]):
continue
connection.poll()
while connection.notifies:
notify = connection.notifies.pop()
self.handle_notify(notify.channel, notify.payload)
Is this approach correct, or should I use separate connection to send
notifications? I know that in general connections are thread safe, but
it is still true if one of the threads calls selects() with the
connection or can this cause a deadlock?
Best regards,
Jan
