I'm writing a pyqt program utilising the Qwizard. From one screen I am running a thread and starting a command line program via Popen. However I'm getting the following warning message:
QObject::connect: Cannot queue arguments of type 'QTextCursor'
(Make sure 'QTextCursor' is registered using qRegisterMetaType().)
The program usually continues but crashes sporadically immediately after this point, leading me to feel that it is related.
As the code of the program is too much to attach, here are the relevant snippets:
class Fee(QThread):
def __init__(self, parent=None, options=None):
QThread.__init__(self, parent)
#set the given options
if options:
self.__options = options
def copy(self, devicename, outputfilename):
self.__device = devicename
self.__outputfile = outputfilename
self.start()
def run(self):
cmd = self.__getCommandLine(self.options, self.__device, self.__outputfile)
logging.info("Running Fee with command %s" % (cmd))
#start the process
output = ""
process = Popen(shlex.split(cmd), stdout= PIPE, stderr= STDOUT)
stderr = process.communicate()[1]
class FeeManager(QtCore.QObject):
def copyAndVerify(self):
self.__fee = Fee(self, self.options)
self.connect(self.__fee, QtCore.SIGNAL("finished()"), self._setCopyFinished)
self.connect(self.__fee, QtCore.SIGNAL("progressUpdated(QString, int, QString)"), self._setCopyProgress)
devicename = self.device.blockdevice
self.__image_outputfilename = "output_file.img")
self.__fee.copy(devicename, self.__image_outputfilename)
class FeeWizardPage(QtGui.QWizardPage):
def initializePage(self):
#already earlier in another wizard page is the following: self.feemanager = FeeManager(self, info)
self.connect(self.wizard().feemanager, QtCore.SIGNAL("copyProgressUpdated(QString, int, QString)"), self.updateCopyProgress)
self.connect(self.wizard().feemanager, QtCore.SIGNAL("verifyProgressUpdated(QString, int, QString)"), self.updateVerifyProgress)
self.connect(self.wizard().feemanager, QtCore.SIGNAL("finished(PyQt_PyObject)"), self.setDone)
self.wizard().feemanager.copyAndVerify()
What am I doing wrong? How can I avoid this message and hopefully bring some stability to the program. I've searched the internet and this forum, and while I've tried a number of suggestions for others, none have worked for this problem. Even when I comment out all signals and connects, I still get the same warning message.
Can someone help?
Thanks a lot.
Related
Problem
Hey, recently when I'm using pyqt6's QProcess, I try to use os.kill() to kill a QProcess's instance. (The reason why I want to use os.kill() instead of QProcess().kill() is that I want to send a CTRL_C_EVENT signal when killing the process.) Even though with using correct pid (acquired by calling QProcess().processId()), it seems that a signal would be sent to all processes unexpectedly.
Code
Here's my code:
from PyQt6.QtCore import QProcess
import os
import time
import signal
process_a = QProcess()
process_a.start("python", ['./test.py'])
pid_a = process_a.processId()
print(f"pid_a = {pid_a}")
process_b = QProcess()
process_b.start("python", ['./test.py'])
pid_b = process_b.processId()
print(f"pid_b = {pid_b}")
os.kill(pid_a, signal.CTRL_C_EVENT)
try:
time.sleep(1)
except KeyboardInterrupt:
print("A KeyboardInterrupt should not be caught here.")
process_a.waitForFinished()
process_b.waitForFinished()
print(f"process_a: {process_a.readAll().data().decode('gbk')}")
print(f"process_b: {process_b.readAll().data().decode('gbk')}")
and ./test.py is simple:
import time
time.sleep(3)
print("Done")
What I'm expecting
pid_a = 19956
pid_b = 28468
process_a:
process_b: Done
What I've got
pid_a = 28040
pid_b = 23708
A KeyboardInterrupt should not be caught here.
process_a:
process_b:
Discussion
I don't know whether this is a bug or misusage. It seems that signal.CTRL_C_EVENT is sent to all processes. So, how do I kill one QProcess instance with signal CTRL_C_EVENT correctly?
I am running a script that acts as a server, allows two clients to connect to it, and for one specific client to send a message to the server, the server modifies it, then sends it to the other client.
This appears to work, as the receiving client acknowledges that the input was received and is valid. This is a script that I intend to run continuously.
However, a big issue is that my /tmp/ directory is filling up with directories named _M... (The ellipses representing a random string), that contains python modules (such as cryptography, which, as far as I'm aware, I'm not using), and timezone information (quite literally every timezone that python supports). It seems to be creating them very frequently, but I can't identify what in the process exactly is doing this.
I have created a working cleanup bash script that removes files older than 5 minutes from the directory every 5 minutes, however, I cannot guarantee that when I am duplicating this process for other devices, that the directories will have the same name formatting. Rather than create a unique bash script for each process that I create, I'd rather be able to clean up the directories from within the python script, or even better, to prevent the directories from being created at all.
The problem is, I'm not certain of how this is accomplished, and I do not see anything on SO regarding what is creating these directories, nor how to delete them.
The following is my script
import time, socket, os, sys, re, select
IP = '192.168.109.8'
PORT = [3000, 3001]
PID = str(os.getpid())
PIDFILE = "/path/to/pidfile.pid"
client_counter = 0
sockets_list = []
def runCheck():
if os.path.isfile(PIDFILE):
return False
else:
with open(PIDFILE, 'w') as pidfile:
pidfile.write(PID)
return True
def openSockets():
for i in PORT:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((IP, i))
s.listen(1)
sockets_list.append(s)
def receiveMessage(client_socket):
try:
message = client_socket.recv(2048).decode('utf-8')
if not message:
return False
message = str(message)
return message
except:
return False
def fixString(local_string):
#processes
return local_string
def main():
try:
openSockets()
clients = {}
print(f'Listening for connections on {IP}:{PORT[0]} and {PORT[1]}...')
client_count = 0
while True:
read_sockets, _, exception_sockets = select.select(sockets_list, [], sockets_list)
for notified_socket in read_sockets:
if notified_socket == sockets_list[0] or notified_socket == sockets_list[1]:
client_socket, client_address = sockets_list[client_count].accept()
client_count = (client_count + 1) % 2
sockets_list.append(client_socket)
clients[client_socket] = client_socket
print('Accepted new connection from: {}'.format(*client_address))
else:
message = receiveMessage(notified_socket)
if message is False:
continue
message = fixString(message)
for client_socket in clients:
if client_socket != notified_socket:
if message != "N/A":
client_socket.send(bytes(message, "utf-8"))
for notified_socket in exception_sockets:
sockets_list.remove(notified_socket)
del clients[notified_socket]
time.sleep(1)
except socket.timeout:
for i in sockets_list:
i.close()
os.remove(PIDFILE)
sys.exit()
except Exception as e:
for i in sockets_list:
i.close()
err_details = str('Error in line {}'.format(sys.exc_info()[-1].tb_lineno), type(e).__name__, e)
os.remove(PIDFILE)
print("Exception: {}".format(err_details))
sys.exit()
if __name__ == "__main__":
if runCheck():
main()
else:
pass
How might I set it up so that the python script will delete the directories it creates in the /tmp/ directory, or better, to not create them in the first place? Any help would be greatly appreciated.
As it would turn out, it is PyInstaller that was generating these files. In the documentation, it states that pyinstaller generates this _MEI directory when creating the executable in single-file mode, and it is supposed to delete it as well, but for some reason it didn't.
This question is two-fold.
1. So I need to run code for a socket server that's all defined and created in another.py, Clicking run on PyCharm works just fine, but if you exec() the file it just runs the bottom part of the code.
There are a few answers here but they are conflicting and for Python 2.
From what I can gather there are three ways:
- Execfile(), Which I think is Python 2 code.
- os.system() (But I've seen it be said that it's not correct to pass to the OS for this)
- And subprocess.Popen (unsure how to use this either)
I need this to run in the background, it is used to create threads for sockets for the recv portion of the overall program and listen on those ports so I can input commands to a router.
This is the complete code in question:
import sys
import socket
import threading
import time
QUIT = False
class ClientThread(threading.Thread): # Class that implements the client threads in this server
def __init__(self, client_sock): # Initialize the object, save the socket that this thread will use.
threading.Thread.__init__(self)
self.client = client_sock
def run(self): # Thread's main loop. Once this function returns, the thread is finished and dies.
global QUIT # Need to declare QUIT as global, since the method can change it
done = False
cmd = self.readline() # Read data from the socket and process it
while not done:
if 'quit' == cmd:
self.writeline('Ok, bye. Server shut down')
QUIT = True
done = True
elif 'bye' == cmd:
self.writeline('Ok, bye. Thread closed')
done = True
else:
self.writeline(self.name)
cmd = self.readline()
self.client.close() # Make sure socket is closed when we're done with it
return
def readline(self): # Helper function, read up to 1024 chars from the socket, and returns them as a string
result = self.client.recv(1024)
if result is not None: # All letters in lower case and without and end of line markers
result = result.strip().lower().decode('ascii')
return result
def writeline(self, text): # Helper func, writes the given string to the socket with and end of line marker at end
self.client.send(text.strip().encode("ascii") + b'\n')
class Server: # Server class. Opens up a socket and listens for incoming connections.
def __init__(self): # Every time a new connection arrives, new thread object is created and
self.sock = None # defers the processing of the connection to it
self.thread_list = []
def run(self): # Server main loop: Creates the server (incoming) socket, listens > creates thread to handle it
all_good = False
try_count = 0 # Attempt to open the socket
while not all_good:
if 3 < try_count: # Tried more than 3 times without success, maybe post is in use by another program
sys.exit(1)
try:
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # Create the socket
port = 80
self.sock.bind(('127.0.0.1', port)) # Bind to the interface and port we want to listen on
self.sock.listen(5)
all_good = True
break
except socket.error:
print('Socket connection error... Waiting 10 seconds to retry.')
del self.sock
time.sleep(10)
try_count += 1
print('Server is listening for incoming connections.')
print('Try to connect through the command line with:')
print('telnet localhost 80')
print('and then type whatever you want.')
print()
print("typing 'bye' finishes the thread. but not the server",)
print("eg. you can quit telnet, run it again and get a different ",)
print("thread name")
print("typing 'quit' finishes the server")
try:
while not QUIT:
try:
self.sock.settimeout(0.500)
client = self.sock.accept()[0]
except socket.timeout:
time.sleep(1)
if QUIT:
print('Received quit command. Shutting down...')
break
continue
new_thread = ClientThread(client)
print('Incoming Connection. Started thread ',)
print(new_thread.getName())
self.thread_list.append(new_thread)
new_thread.start()
for thread in self.thread_list:
if not thread.isAlive():
self.thread_list.remove(thread)
thread.join()
except KeyboardInterrupt:
print('Ctrl+C pressed... Shutting Down')
except Exception as err:
print('Exception caught: %s\nClosing...' % err)
for thread in self.thread_list:
thread.join(1.0)
self.sock.close()
if "__main__" == __name__:
server = Server()
server.run()
print('Terminated')
Notes:
This is created in Python 3.4
I use Pycharm as my IDE.
One part of a whole.
2. So I'm creating a lightning detection system and this is how I expect it to be done:
- Listen to the port on the router forever
The above is done, but the issue with this is described in question 1.
- Pull numbers from a text file for sending text message
Completed this also.
- Send http get / post to port on the router
The issue with this is that i'm unsure how the router will act if I send this in binary form, I suspect it wont matter, the input commands for sending over GSM are specific. Some clarification may be needed at some point.
- Recieve reply from router and exception manage
- Listen for relay trip for alarm on severe or close strike warning.
- If tripped, send messages to phones in storage from text file
This would be the http get / post that's sent.
- Wait for reply from router to indicate messages have been sent, exception handle if it's not the case
- Go back to start
There are a few issues I'd like some background knowledge on that is proving hard to find via the old Google and here on the answers in stack.
How do I grab the receive data from the router from another process running in another file? I guess I can write into a text file and call that data but i'd rather not.
How to multi-process and which method to use.
How to send http get / post to socket on router, post needed occording to the router manual is as follows: e.g. "http://192.168.1.1/cgi-bin/sms_send?number=0037061212345&text=test"
Notes: Using Sockets, threading, sys and time on Python 3.4/Pycharm IDE.
Lightning detector used is LD-250 with RLO Relay attached.
RUT500 Teltonica router used.
Any direction/comments, errors spotted, anything i'm drastically missing would be greatly appreciated! Thank you very much in advance :D constructive criticism is greatly encouraged!
Okay so for the first part none of those suggested in the OP were my answer. Running the script as is from os.system(), exec() without declaring a new socket object just ran from __name__, this essentially just printed out "terminated", to get around this was simple. As everything was put into a classes already, all I had to do is create a new thread. This is how it was done:
import Socketthread2
new_thread = Socketthread2.Server() # Effectively declaring a new server class object.
new_thread.run()
This allowed the script to run from the beginning by initialising the code from the start in Socket, which is also a class of Clientthread, so that was also run too. Running this at the start of the parent program allowed this to run in the background, then continue with the new code in parent while the rest of the script was continuously active.
I have the need to download all files in an ftp directory. I don't know the files in the dir at the time my program starts, so I want the program to list the contents of the dir, then download each of the files it finds.
I've made a little demo script that downloads a file from ftp & updates a progress bar while doing so. The downloading & updating the progress bar works fine, however, I'm trying to do the next step which is to list the contents of some dir & download the files, and that part isn't working.
At the moment, I'm just trying to do a list on any directory & print the results to the command line.
When I try to do a listInfo.connect, I get an error message:
QObject::connect: Cannot queue arguments of type 'QUrlInfo'
(Make sure 'QUrlInfo' is registered using qRegisterMetaType().)
... as I understand it, qRegisterMetaType is not something that can be done in PyQt & is also a sign of a fundamental problem, and herein lies my problem. I can do a commandFinished.connect and dataTransferProgress.connect without issue, but listInfo.connect doesn't seem to work (as I would expect it).
Any ideas how to correct this?
Here's some example code (pardon the length). I would like to be able to print the listed files/urls from the function "lister". Ultimately, I'd like to then have that function formulate new urls & pass them back to connectAndDownload to download each of the files (of course, this will require modifications to connectAndDownload, but we're not there yet).
#!/usr/bin/env python
from PyQt4 import QtCore, QtGui, QtNetwork
class FtpWorker(QtCore.QThread):
dataTransferProgress = QtCore.pyqtSignal(int,int)
def __init__(self,url,parent=None):
super(FtpWorker,self).__init__(parent)
self.ftp = None
self.outFile = None
self.get_index = -1
self.url = url
def run(self):
self.connectAndDownload()
self.exec_()
def ftpCommandFinished(self, command_index, error):
print "-----commandfinished-----",command_index
if self.ftp.currentCommand == QtNetwork.QFtp.ConnectToHost:
if error:
QtGui.QMessageBox.information(self, "FTP",
"Unable to connect to the FTP server at %s. Please "
"check that the host name is correct.")
return
if self.ftp.currentCommand == QtNetwork.QFtp.Get or command_index == self.get_index:
if error:
print "closing outfile prematurely"
self.outFile.close()
self.outFile.remove()
else:
print "closed outfile normally"
self.outFile.close()
self.outFile = None
def ftpDataTransferProgress(self,a,b):
self.dataTransferProgress.emit(a,b)
def lister(self,url_info):
print url_info.name()
def connectAndDownload(self):
if self.ftp:
self.ftp.abort()
self.ftp.deleteLater()
self.ftp = None
return
self.ftp = QtNetwork.QFtp()
self.ftp.commandFinished.connect(self.ftpCommandFinished)
self.ftp.listInfo.connect(self.lister)
self.ftp.dataTransferProgress.connect(self.ftpDataTransferProgress)
url = QtCore.QUrl(self.url)
print "connect",self.ftp.connectToHost(url.host(), url.port(21))
print "login",self.ftp.login(url.userName(), url.password())
print "Connecting to FTP server %s..." % str(url.host())
import os
fileName = os.path.basename(self.url)
if QtCore.QFile.exists(fileName):
print "removing '%s'" % fileName
os.unlink(fileName)
self.outFile = QtCore.QFile(fileName)
if not self.outFile.open(QtCore.QIODevice.WriteOnly):
QtGui.QMessageBox.information(self, "FTP",
"Unable to save the file %s: %s." % (fileName, self.outFile.errorString()))
self.outFile = None
return
tmp = self.ftp.list()
print "starting list",tmp
print "ftp.get(%s,%s)" % (str(url.path()), self.outFile)
self.get_index = self.ftp.get(url.path(), self.outFile)
class AddProgresWin(QtGui.QWidget):
def __init__(self, parent=None):
super(AddProgresWin, self).__init__(parent)
self.thread = FtpWorker(url="ftp://ftp.qt.nokia.com/developerguides/qteffects/screenshot.png")
self.thread.dataTransferProgress.connect(self.updateDataTransferProgress)
self.nameLabel = QtGui.QLabel("0.0%")
self.nameLine = QtGui.QLineEdit()
self.progressbar = QtGui.QProgressBar()
mainLayout = QtGui.QGridLayout()
mainLayout.addWidget(self.progressbar, 0, 0)
mainLayout.addWidget(self.nameLabel, 0, 1)
self.setLayout(mainLayout)
self.setWindowTitle("Processing")
self.thread.start()
def updateDataTransferProgress(self, readBytes, totalBytes):
self.progressbar.setMaximum(totalBytes)
self.progressbar.setValue(readBytes)
perct = "%2.1f%%" % (float(readBytes)/float(totalBytes)*100.0)
self.nameLabel.setText(perct)
if __name__ == '__main__':
import sys
app = QtGui.QApplication(sys.path)
pbarwin = AddProgresWin()
pbarwin.show()
sys.exit(app.exec_())
It appears that this is a Qt bug. From Phil Thompson, "It's arguably a Qt bug -it should call qRegisterMetaType() itself for any types used in signal arguments."
It was also brought to my attention that for this purpose, there's no need to thread, as QFtp is asynchronous & comes with its own signals. I've reimplemented the ftp.list() (and associated signal handling) in the main thread & all is well.
I have a TCP client communicating with a LabVIEW GUI.
My program calls connect() at the start and disconnect() at the end. It will call passCommand(x) to read or write data to the LabVIEW GUI. However, in some cases, I have multiple threads which may be calling passCommand() and somehow the return data will get mixed up.
For example, in the main thread I will ask for the voltage, which should be a number between 300 and 400. In a different thread I will ask for the temperature, which should be a number from 0-100. The voltage will be returned as 25, while the temperature will get 250.
Is this a known issue with TCP communication and threading? Is there a way to solve this such as implementing a queue or unique id or something?
import socket as _socket
# get python major version as integer
from sys import version as pythonVersion
pythonVersionMajor = int(pythonVersion[0])
_serverHost = 'localhost'
_serverPort = 50007
isConnected = 0
_sockobj = None
_error_string = "error:"
def connect():
'opens a connection to LabVIEW Server'
global _sockobj, isConnected
_sockobj = _socket.socket(_socket.AF_INET, _socket.SOCK_STREAM) # create socket
_sockobj.connect((_serverHost, _serverPort)) # connect to LV
isConnected = 1
def disconnect():
'closes the connection to LabVIEW Server'
global isConnected
_sockobj.close() # close socket
isConnected = 0
def passCommand(command):
'passes a command to LabVIEW Server'
## We prepend the command length (8 char long) to the message and send it to LV
# Compute message length and pad with 0 on the left if required
commandSize=str(len(command)).rjust(8,'0')
# Prepend msg size to msg
completeCommand=commandSize+command
# python 3 requires data to be encoded
if (pythonVersionMajor >= 3):
completeCommand = str.encode(completeCommand)
# Send complete command
_sockobj.send(completeCommand)
data = _sockobj.recv(11565536)
# python 3 requires data to be decoded
if (pythonVersionMajor >= 3):
data = bytes.decode(data)
if data.rfind(_error_string) == 0:
error = True
data = data[len(_error_string):] # get data after "error:" string
else:
error = False
execString = "lvdata = " + data
exec(execString, globals())
if error:
raise _LabVIEWError(lvdata)
else:
return lvdata
class _Error(Exception):
"""Base class for exceptions in this module."""
pass
class _LabVIEWError(_Error):
"""Exception raised for errors generated in LabVIEW.
Attributes:
code -- LabVIEW Error Code
source -- location of the error
message -- explanation of the error
"""
def __init__(self, error):
self.code = error[0]
self.source = error[1]
self.message = error[2]
def __str__(self):
return "%s" % (self.message,)
This is an example of one of the most common problems with threading. You are accessing a resource from multiple threads and the resource is not considered thread-safe (if both threads are sending/receiving at the same time, it's possible for a thread to get the wrong response, or even both responses).
Ideally you should be locking access to passCommand with a mutex so it can only be used with by one thread at a time, or opening one socket per thread, or doing all of your socket operations in a single thread.