On 9/15/2011 1:19 AM, pyt...@bdurham.com wrote:
Is there a way to cancel or timeout a long running regular expression? I have a program that accepts regular expressions from users and I'm concerned about how to handle worst case regular expressions that seem to run forever. Ideally I'm looking for a way to evaluate a regular expression and timeout after a specified time period if the regular expression hasn't completed yet. Or a way for a user to cancel a long running regular expression.
This is a general problem when evaluating *any* expression from the outside. [0]*10000*10000 will eat space as well as time. At least, as far as I know, an re cannot cause a disk reformat ;-).
There have been previous discussions on this generally topic.
I was thinking there might be a technique I could use to evaluate regular expressions in a thread or another process launched via multiprocessing module and then kill the thread/process after a specified timeout period.
Only solution I remember ever seen posted. I wonder if there are any heuristics for detecting exponential time re's.
> My concern about the multiprocessing module
technique is that launching a process for every regex evaluation sounds pretty inefficient. And I don't think the threading module supports the ability to kill threads from outside a thread itself.
-- Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
