On Wed, 24 May 2006 06:49:23 +1000, Paul Moore
I have a program where I think that what I want to use is deferToThread and setTimeout. However, the setTimeout method is marked as deprecated - but I can't find a good supported alternative. Can anyone help?
You can just use reactor.callLater(...) to run whatever timeout code you have after the given number of seconds. callLater returns a DelayedCall instance which you can .cancel() if you get a result before the timeout.
The situation I have is:
I need to do a large-ish number (50-100) of blocking calls in parallel, and collect the results or any errors. In itself, this seems like a suitable use for deferToThread (defer each call, and collect the results in the deferred callback/errback).
The problem is that in rare cases, the blocking call can block indefinitely. In this case, I need to make the call time out. However, the underlying API offers no way to time out the call, so I have to do this externally.
Well this is a bit of a problem. You can't just kill a thread - so it will eventually return a result, and Twisted will .callback() its deferred. If you've already stepped in, due to a timeout, and .callback()'ed the same deferred you'll get an AlreadyCalledError in your log. So don't do that.. don't fire that deferred. When you time out just keep some state so that you can ignore the result if and when it comes.
A quick prototype seems to work OK, using setTimeout to force a timeout on the deferred, but it generates deprecation warnings for the setTimeout call.
What should I be using to achieve this effect?
Thanks, Paul.
Hope that helps. -- Eric Mangold - Twisted/Win32 Maintainer http://twistedmatrix.com/trac/wiki/Windows