The way I do this is I isolate all the COM stuff in a separate thread from thread that runs my reactor.
This thread starts by calling: pythoncom.CoInitializeEx(pythoncom.COINIT_APARTMENTTHREADED) it then creates the COM object and runs an event loop something like this: while keepRunning: n = MsgWaitForMultipleObjects(handles, False, timeout, QS_ALLINPUT) if n == WAIT_OBJECT_0 + nHandles: # There is a win32 message waiting. if pythoncom.PumpWaitingMessages(): keepRunning = False I send messages to the thread by putting them in a queue and setting an event. The messages cause methods to be called on the COM object. I send the results of the COM methods back to the reactor thread using reactor.callFromThread(). It's a bit of effort to do this, but it works really well. It's been in production for several years and I've never had a problem with it. Hope this helps, Hugh On Tue, Jun 29, 2010 at 10:43 AM, Don Dwiggins <ddwigg...@advpubtech.com> wrote: > > I need to create a COM object in a Windows application, and call it. > Since the call will take some time to execute, I wrap it in a deferToThread. > > I've found that, when I create the object inline, it works. However, > when I defer it, it hangs up in the win32com.client.Dispatch call. I've > tried several things, including digging into the guts of Dispatch -- the > hangup occurs during the creation of the object. > > I've discussed this with Mark Hammond, who suggests one lead: > > "The Windows message loop is used by the COM marshalling process. IIRC, > the first thread to initialize COM in a process is the thread in which > single-threaded objects will always end up being called in. If a > different thread creates the object, COM uses Windows messages to > marshall all calls back to that main thread. IOW, your second thread > makes a call - even to create the object - which results in that thread > sending a windows message to the main thread to act on the request. > > What this probably means in practice is that twisted needs to use a > reactor which calls MsgWaitForMultipleObjects() and runs a message loop > when the function detects a new message is in the queue. I'm not sure > if there is an existing reactor which does this." > > I'm posting this on the off chance that someone else has wandered into > this corner of Windows arcana, and has come up with something useful. > > I'm about to give up on doing this "inside" the twisted app, and running > it in a separate app that I'll call from the thread. > > TIA, > -- > Don Dwiggins > Advanced Publishing Technology > > > _______________________________________________ > Twisted-Python mailing list > Twisted-Python@twistedmatrix.com > http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python _______________________________________________ Twisted-Python mailing list Twisted-Python@twistedmatrix.com http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
