ROS错误。处理请求时出错：信号仅在主线程&quot；中工作。

问题描述

我正在使用Robot操作系统(ROS)，并尝试创建一个服务器/客户端，其中服务器将引导客户端指定的ROS节点。要执行"启动"，我使用的是基于以下建议的rosLaunch：http://wiki.ros.org/roslaunch/API%20Usage

我可以在窗口中运行rocore，然后我可以运行启动良好的服务器。但是，只要我尝试通过客户端发送要引导的节点名，就会收到以下错误：

"错误处理请求：信号仅在主线程中工作"

然后它指向一些我尚未追踪到的各个领域的文件。

我已经尝试在我为要启动的节点(在本例中为turtlesim_node和turtle_telop_key)单独创建的每个启动文件上使用一个简单的rosunch调用，它们启动良好，只需运行rosLaunch[Package]turtlesim_Launch.Launch等即可运行。

以下是我的服务器的代码：

#!/usr/bin/env python
#Filename: primary_server.py

import rospy
import roslaunch
from robot_man.srv import *

class StartUpServer(object):
    def __init__(self):
        self._nodes = []


    def handle_startup(self, names):
        self._temp = names.nodes.split(",") #This reades in the
        # information from the srv file sent by the client and
        # separates each node/package pair

        #This loop separates the input from pairs of 2 corresponding
        # to the package and node names the user inputs
        for i in range(len(self._temp)):
            self._nodes.append(self._temp[i].split())

        #This loop will launch each node that the user has specified
        for package, executable in self._nodes:
            print('package is: {0}, executable is: {1}'.format(package, executable))
            node = roslaunch.core.Node(package, executable)
            launch = roslaunch.scriptapi.ROSLaunch()
            launch.start()

            process = launch.launch(node)
            print('running node: %s'%executable)
        return StartUpResponse(self._nodes) #I will change this later


if __name__ == '__main__':
    rospy.init_node('startup_node')
    server = StartUpServer()
    rospy.Service('startup', StartUp, server.handle_startup)
    print('The servers are up and running')
    rospy.spin()

以下是我的客户端的代码：

#!/usr/bin/env python
#Filename: primary_client_startup.py

import rospy
from robot_man.srv import *

def main(nodes):
    rospy.wait_for_service('startup')
    proxy = rospy.ServiceProxy('startup', StartUp)
    response = proxy(nodes)
    return response

if __name__ == '__main__':
    nodes = input('Please enter the node packages followed by 
    node names separated by spaces. 
 To activate multiple nodes 
    separate entries with a comma > ')
    main(nodes)

这是我的srv文件：

#This should be a string of space/comma separated values
string nodes
---
#This should return "success" if node/s start up successfully, else "fail"
string status

最后，以下是我为启动海龟模拟器而创建的两个启动文件：

turtlesim_Launch.Launch

<launch>
    <node name="turtlesim_node" pkg="turtlesim" type="turtlesim_node" />
</launch>

Turtle_Teleop_Launch.Launch

<launch>
    <node name="turtle_teleop_key" pkg="turtlesim" type="turtle_teleop_key" />
</launch>

我在谷歌上搜索了一下，没有发现ROS有类似的问题(尽管Django等有一些类似的错误，但它们没有关联)。

感谢您的帮助！

附注。值得注意的是，当出现错误时，我会转到第34行(process=Launch.Launch(Node))。

---

解决方案

实际上是文档中提到的

您没有从Python主线程调用init_node()。Python仅允许从主线程注册信号。

查看此处rospyOverviewInitialization and Shutdown