On 18 ago, 04:31, Graham Dumpleton <[EMAIL PROTECTED]> wrote: > If one creates a thread using threading.Thread and makes it a daemon > by calling setDaemon(), then when Python is exiting it will not > attempt to call join() on that thread and wait for it to complete > first. [...] > End result is that it could result in a Python exception at some > point, evidenced by messages starting with: > Exception in thread Thread-1 (most likely raised during interpreter > shutdown) [...] > > In order to avoid this, do people think that as an alternative to > creating daemonised thread that it would be reasonable to create a > derived Thread class for the particular task which overrides > Thread.join() method to set some flag or otherwise take some action > that the thread would notice to tell it to stop, and then call base > class Thread.join(). > > This way you can flag the thread to shutdown automatically when Python > is going around calling join() on non daemonised threads. > > Or am I missing the obvious as far as ways of flagging threads to tell > them to stop? > > Note that this is where Python is being used embedded in a C program. > There is no Python main function where code can be put to signal > threads to otherwise stop.
This last statement is important. You need "some" way to tell the threads to stop working. Usually the thread's run() method is a big loop; you need to tell it somehow to exit the loop. By example, if you are using a Queue, put a sentinel object in it; or use an Event object; or at least a global variable. Overriding thread.join() as you suggest above may be a good place to do that, if you don't have another chance. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
