I've attached my current code, which seems to be working. This will hopefully be checked in today, but some testing by others would be useful. """ Win32 process support. """ # Twisted imports from twisted.internet import task, abstract # System imports import win32api import win32pipe import win32file import win32process import win32security import win32con import win32event import pywintypes import msvcrt import os import sys import threading import Queue import string class Process(abstract.FileDescriptor): """A process that integrates with the Twisted event loop.""" buffer = '' def __init__(self, command, args, environment, path): # security attributes for pipes sAttrs = win32security.SECURITY_ATTRIBUTES() sAttrs.bInheritHandle = 1 # create pipes hStdin_r, self.hStdin_w = win32pipe.CreatePipe(sAttrs, 0) self.hStdout_r, hStdout_w = win32pipe.CreatePipe(sAttrs, 0) self.hStderr_r, hStderr_w = win32pipe.CreatePipe(sAttrs, 0) # set the info structure for the new process. StartupInfo = win32process.STARTUPINFO() StartupInfo.hStdInput = hStdin_r StartupInfo.hStdOutput = hStdout_w StartupInfo.hStdError = hStderr_w StartupInfo.dwFlags = win32process.STARTF_USESTDHANDLES # Mark doesn't support wShowWindow yet. # StartupInfo.dwFlags = StartupInfo.dwFlags | win32process.STARTF_USESHOWWINDOW # StartupInfo.wShowWindow = win32con.SW_HIDE # Create new output read handles and the input write handle. Set # the inheritance properties to FALSE. Otherwise, the child inherits # the these handles; resulting in non-closeable handles to the pipes # being created. pid = win32api.GetCurrentProcess() tmp = win32api.DuplicateHandle( pid, self.hStdin_w, pid, 0, 0, # non-inheritable!! win32con.DUPLICATE_SAME_ACCESS) # Close the inhertible version of the handle win32file.CloseHandle(self.hStdin_w) self.hStdin_w = tmp tmp = win32api.DuplicateHandle( pid, self.hStdout_r, pid, 0, 0, # non-inheritable! win32con.DUPLICATE_SAME_ACCESS) # Close the inhertible version of the handle win32file.CloseHandle(self.hStdout_r) self.hStdout_r = tmp tmp = win32api.DuplicateHandle( pid, self.hStderr_r, pid, 0, 0, # non-inheritable! win32con.DUPLICATE_SAME_ACCESS) # Close the inhertible version of the handle win32file.CloseHandle(self.hStderr_r) self.hStderr_r = tmp # start the process. print "creating process" cmdline = "%s %s" % (command, string.join(args, ' ')) hProcess, hThread, dwPid, dwTid = win32process.CreateProcess( None, # program cmdline,# command line None, # process security attributes None, # thread attributes 1, # inherit handles, or USESTDHANDLES won't work. # creation flags. Don't access the console. 0, # Don't need anything here. # If you're in a GUI app, you should use # CREATE_NEW_CONSOLE here, or any subprocesses # might fall victim to the problem described in: # KB article: Q156755, cmd.exe requires # an NT console in order to perform redirection.. environment, # new environment path, # new directory StartupInfo) # normally, we would save the pid etc. here... print "process created" # Child is launched. Close the parents copy of those pipe handles # that only the child should have open. # You need to make sure that no handles to the write end of the # output pipe are maintained in this process or else the pipe will # not close when the child process exits and the ReadFile will hang. win32file.CloseHandle(hStderr_w) win32file.CloseHandle(hStdout_w) win32file.CloseHandle(hStdin_r) self.outQueue = Queue.Queue() self.closed = 0 threading.Thread(target=self.doWrite).start() threading.Thread(target=self.doReadOut).start() threading.Thread(target=self.doReadErr).start() def write(self, data): """Write data to the process' stdin.""" self.outQueue.put(data) def closeStdin(self): """Close the process' stdin.""" self.outQueue.put(None) def connectionLost(self): """Will be called twice, by the stdout and stderr threads.""" if not self.closed: abstract.FileDescriptor.connectionLost(self) print "connection lost" self.closed = 1 self.closeStdin() win32file.CloseHandle(self.hStdout_r) win32file.CloseHandle(self.hStderr_r) def doWrite(self): """Runs in thread.""" while 1: data = self.outQueue.get() if data == None: break try: win32file.WriteFile(self.hStdin_w, data, None) except win32api.error: break win32file.CloseHandle(self.hStdin_w) def doReadOut(self): """Runs in thread.""" while 1: try: hr, data = win32file.ReadFile(self.hStdout_r, 8192, None) except win32api.error: task.schedule(self.connectionLost) return task.schedule(self.handleChunk, data) def doReadErr(self): """Runs in thread.""" while 1: try: hr, data = win32file.ReadFile(self.hStderr_r, 8192, None) except win32api.error: task.schedule(self.connectionLost) return task.schedule(self.handleError, data) if __name__ == '__main__': from twisted.internet import main def printer(x): print "Got", repr(x) exe = win32api.GetModuleFileName(0) print exe p = Process(exe, ['-u', 'processtest.py'], None, None) print "ok, made process object" p.handleChunk = printer p.handleError = printer p.write("hello, world") p.closeStdin() main.run()