[Twisted-Python] spawnProcess under Win32

Michael Li mli at deform.com
Mon Aug 14 11:34:48 EDT 2006

I've recently fixed a problem in MPI 1.2.1 launching program RemoteShell.
It uses CreateProcessAsUser to spawn a process. The RemoteShell runs
as a service(daemon) and spawn a new process perfectly (without DOS
window). The followings are C-code, it might give you some hint.
        if (CreateProcess(
            NULL, NULL, TRUE,
            &saInfo, &psInfo))

Igor Kravtchenko wrote:
> Hi,
> yes I see your point of view.
> I deliberately passed that Win32 flags since I didn't wanted to get in 
> details
> of what kind of Win32 features we need or not.
> It can indeed potentially breaks Twisted behavior if incorrect flags 
> are passed.
> However it's just easier even if less secure.  Otherwise, you have to 
> enumerate
> all kind of features users want and implement them explicitly while 
> having the
> correct code guard to prevent from crash or incorrect behavior.
> I don't know about other Win32 developpers.  From my side, I just wanted
> a way to prevent a console to be opened, so might be something like an
> explicit CREATE_NO_CONSOLE flag or such.
> Igor.
> glyph at divmod.com wrote:
>> On Mon, 14 Aug 2006 15:15:55 +0200, Igor Kravtchenko 
>> <igor at mekensleep.com> wrote:
>>> Hi!
>>> I've looked at the way Twisted creates a process under Win32 and 
>>> I've noticed
>>> that it uses the CreateProcess() function.  The problem is it 
>>> doesn't mention any
>>> creation flags (i.e.: it just passes 0) whereas here, we would need 
>>> to pass
>>> DETACHED_PROCESS to avoid a new console to be created.
>>> I would be interested to know what do you think about this?
>>> Does it seem to you a good idea?
>> Well, we do have a UNIX-specific argument to spawnProcess (usePTY), 
>> so I don't see why we couldn't have a Win32-specific argument as 
>> well.  However, "win32flags" seems like a pretty vague name, 
>> especially since it could be CreateProcess's dwCreationFlags argument 
>> or STARTUPINFO's dwFlags attribute.
>> Also, depending on context, you might want CREATE_NO_WINDOW or 
>> DETACHED_PROCESS or possibly both.
>> I believe the right thing to do is to come up with some typical 
>> features of the Windows process environment and support them 
>> explicitly.  I don't believe all the flags you can pass to 
>> CreateProcess are compatible with the way Twisted expects 
>> subprocesses to behave, and I am definitely sure that not all the 
>> things you can put in STARTUPINFO are.
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