Hello all, I'm pretty new to twisted activity (just some doc and code reading so far). So please be forbearing if the answers to the following questions are obvious. I'm wrapping some C library which implements some networked client to use it from python, i.e. from a twisted app. Within the guts of this lib there is a thread created (i.e. it is normally never seen by python). This thread manages some heartbeat mechanism. I, as a user of this API, can register a callback with the lib. This callback is called _within the context of this underground thread_, when the connection to the server is lost (as recognised through the heartbeat). Now my first question is, how you would stuff that event (loss of server connection) into the core event loop? One possibility that I see would be to let my registered C-callback signal some sort of a synchronisation item (like mutex or so) whenever the connection to the server is lost. Then I'm using a threaded deferred to block on this synchronisation item, triggering the deferred's callback mechanism when the item gets signaled. But this approach seems very wasteful to me, as I'm using a deferred and a thread for an event that will never happen (my own application is a long running process either). Actually I'm wrapping not only one but two such C libraries. Both implement protocols that are not (yet?) available for python/twisted and that are not trivial (just to illustrate that there are not many alternatives to using these C libs). I'm planning to use both of them through twisted's thread pool mechanism. The only thing is that I would like to have fine grained control over the number of threads used for each of them. Is it possible to create custom thread pools besides the default one? If so, is there anything preventing me from creating a thread pool with only one thread? TIA, andreas