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hello! I wrote a python parent script which starts a
separate script in a new process (under Windows XP Pro SP2, Python 2.4.1).
Through anonymous pipes I have a bidirectional communication to the
child. Now I embedded the parent script in a CPP program, but when I start the
cpp dummy application it seems as the application is producing copies of itself
(like a recursive function -> in the windows task manager the number of the
same process is increasing) and the child process is not working! But when i
start the parent script directly, it works well. Maybe you can tell me the
reason why it does not work in CPP. Below you can find the the part of the code which is
starting the client process. I hope you can help me. Thank you! Michael Lieschnegg I took following code from a closed forum to create
the child process: class Process: 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) # set the
info structure for the new process.
StartupInfo = win32process.STARTUPINFO()
StartupInfo.hStdInput = hStdin_r
StartupInfo.hStdOutput = hStdout_w
StartupInfo.dwFlags = win32process.STARTF_USESTDHANDLES # 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
# 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) # Child is
launched. Close the parents copy of those pipe handles # that
only the child should have open.
win32file.CloseHandle(hStdout_w)
win32file.CloseHandle(hStdin_r)
self.outQueue = Queue.Queue()
self.closed = 0
self.stdoutClosed = 0
threading.Thread(target=self.doWrite).start() def write(self, data):
self.outQueue.put(data) def closeStdin(self):
self.outQueue.put(None) def connectionLost(self): if not
self.closed:
print "connection lost"
self.closed = 1
self.closeStdin()
win32file.CloseHandle(self.hStdout_r) def doWrite(self): while 1: data = "">
if data == None:
break
try:
win32file.WriteFile(self.hStdin_w, data, None)
except win32api.error:
print "error"
break
win32file.CloseHandle(self.hStdin_w) def doReadOut(self): try:
hr, data = "" 8192, None) except
win32api.error:
self.stdoutClosed = 1
return
self.handleData(data) return
repr(data) def handleData(self, data): print
"Got", repr(data) if __name__ == '__main__': exe =
win32api.GetModuleFileName(0) print exe p = Process(exe, ['-u',
'dispatcher.py', '8888'], None, None) print "ok, made process
object" while 1:
p.write("hello, world! Who you are?\n")
p.doReadOut() When I run this script directly, the client process
(“dispatcher.py”) will be started correctly. But when I create a
instance of the class Process in my cpp application, the client does not start
and the cpp application is producing and starting copies of itself (it
seems so). |
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