Python ros melodic 中的子进程连接被拒绝

Question

我想使用ros melodic包中的子进程进行通信。

因为ros默认使用python2，我在python3库中遇到了一些python版本问题。这就是我决定使用子流程的原因。

这是我的两个代码：第一个是ros的节点（作为客户端），第二个是python3文件作为服务器。
- 客户（image_bus.py）

#!/usr/bin/env python
import rospy
import cv2
import numpy as np
import os
import subprocess
from cv_bridge import CvBridge, CvBridgeError
from std_msgs.msg import String
from sensor_msgs.msg import Image
from json_socket import Client

HOST_IP = "127.0.0.1"
HOST_PORT = 9989

class ImageBus:

    def __init__(self):
        self.sub_video_capture = rospy.Subscriber('/video_capture', Image, self.send_to_face_detector)
        self.cvb = CvBridge()
        self.rate = rospy.Rate(2)
        self.client = Client()


    def send_to_face_detector(self, image):
        try:
            cv_image = self.cvb.imgmsg_to_cv2(image, "bgr8")
        except CvBridgeError as e:
            print(e)

        filename = os.path.dirname(os.path.abspath(__file__)) + "/face_detector.py"

        p = subprocess.Popen(["python3", filename])
        print("p : ", p)
        self.rate.sleep()

        # client = Client()
        c = self.client.connect(HOST_IP, HOST_PORT)

        send_data = {}
        send_data['video_cap'] = cv_image

        self.client.send(send_data)

        recv_data = self.client.recv()
        self.rate.sleep()

        self.client.close()


if __name__ == '__main__':
    rospy.init_node('ImageBus', anonymous=False)
    ib = ImageBus()

    try:
        rospy.spin()
    except rospy.ROSInterruptException:
        pass

服务器(face_detector.py)

import cv2
import numpy as np
import matplotlib.pyplot as plt
import tensorflow as tf
import math
from sklearn.decomposition import PCA
import os
import glob
from jsonsocket import Server

BIND_IP = "127.0.0.1"
BIND_PORT = 9989

class FaceDetector:

    def __init__(self):
        self.socket = Server(BIND_IP, BIND_PORT)

    # Some Codes Here

    def check_face(self, frame):
        # Some codes Here

                return boxed_frame

if __name__=="__main__":
    fd = FaceDetector()
    fd.socket.accept()

    while True:
        print("SERVER")
        recv_image = fd.socket.recv()
        if not recv_image:
            break

        video_cap = recv_data['video_cap']

        face_detected_image = fd.check_face(video_cap)

        send_image = {}
        send_image['face_detected_image'] = face_detected_image

        fd.socket.send(send_image)

    fd.socket.close()

下面的代码是我的jsonsocket.py。

import socket
import json

def _send(socket, send_data):
    json_data = json.JSONEncoder().encode(send_data)
    socket.sendall(json_data.encode()) 


def _recv(socket):
    recv_data = socket.recv(4096)
    json_data = json.loads(recv_data.decode())

    return json_data

class Server(object):
    backlog =1
    client =None


    def __init__(self, host, port):
        self.socket = socket.socket()
        self.socket.bind((host, port))
        self.socket.listen(self.backlog)

    def __del__(self):
        self.close()

    def accept(self):
        if self.client:
            self.client.close()

        self.client, self.client_addr =self.socket.accept()
        return self

    def send(self, data):
        if not self.client:
            raise Exception('Cantnot send data, no client is connected.')

        _send(self.client, data)
        return self

    def recv(self):
        if not self.client:
            raise Exception('Cannot receive data, no client is connected.')

        return _recv(self.client)

    def close(self):
        if self.client:
            self.client.close()
            self.client =None

        if self.socket:
            self.socket.close()
            self.socket =None


class Client(object):
    socket =None

    def __del__(self):
        self.close()

    def connect(self, host, port):
        self.socket = socket.socket()
        self.socket.connect((host, port))
        return self

    def send(self, data):
        if not self.socket:
            raise Exception('You have to connect first before sending data.')           

        _send(self.socket, data)
        return self

    def recv(self):
        if not self.socket:
            raise Exception('You have to connect first before receving data.')

        return _recv(self.socket)

    def close(self):
        if self.socket:
            self.socket.close()
            self.socket =None

当我用我的启动文件 roslaunch 这个包时，它输出：

File "/catkin_ws/src/jetson/src/image_bus.py", line 37, in send_to_face_detector
    c = self.client.connect(HOST_IP, HOST_PORT)
  File "/catkin_ws/src/jetson/src/json_socket.py", line 67, in connect
    self.socket.connect((host, port))
  File "/usr/lib/python2.7/socket.py", line 228, in meth
    return getattr(self._sock,name)(*args)
error: [Errno 111] Connection refused

我该如何解决这个问题？

我试着改了端口号，改了变量名，看看到底是哪里出了问题。但是，我找不到。

请帮帮我。谢谢。

Answer 1

精简起来，这看起来纯粹是您的套接字代码的问题：您正在尝试连接（），而另一端不允许。但是，我注意到您的 socket() 调用是空的；尝试 socket.socket(socket.AF_INET, socket.SOCK_DGRAM) 而不是空调用。仅尝试 isolating/testing server/client，有个解决套接字连接问题的问题。

Python ros melodic 中的子进程连接被拒绝

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