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Action Server timeout across systems

asked 2016-09-11 17:15:43 -0500

anonymous user


I am having trouble with actionlib.SimpleActionClient wait_for_server timing out when the client and server are on different systems and I could use help understanding why. In this case, roscore and the action server is running on a Raspberry Pi and the client is running on an Ubuntu VM. Both are running Indigo. I have a simple example that runs fine when the client and server run on the same computer (the Raspberry Pi). However when I run roscore and the action server on the Raspberry Pi and I run these commands on the Ubuntu client side:

  • rosnode list correctly lists the server node
  • rostopic list correctly lists the topics
  • rosnode ping ping_action_server shows repeated successful pings of about 20 msecs

However, when I run the following client code it fails to connect...

import sys
import rospy
import actionlib

from inmoov.msg import PingAction, PingGoal, PingResult

def onShutdown():
    rospy.loginfo("Shutting down")

    rospy.init_node('ping_client', log_level=rospy.DEBUG)
    client = actionlib.SimpleActionClient('ping', PingAction)
    rospy.loginfo("Waiting for ping action server...")
    finished = client.wait_for_server(timeout = rospy.Duration(10.0))
    if(finished is False): 
        rospy.logerr("Ping action server timed out")
        rospy.loginfo("Ping action server found")

    print("An exception was encountered")
    e = sys.exc_info()[0]
    print str(e)

The output is:

[DEBUG] [WallTime: 1473631183.986657] init_node, name[/ping_client], pid[7947]
[DEBUG] [WallTime: 1473631183.987061] binding to 0
[DEBUG] [WallTime: 1473631183.987256] bound to 35061
[DEBUG] [WallTime: 1473631183.987703] ... service URL is rosrpc://raspberrypi:35061
[DEBUG] [WallTime: 1473631183.987884] [/ping_client/get_loggers]: new Service instance
[DEBUG] [WallTime: 1473631184.003141] ... service URL is rosrpc://raspberrypi:35061
[DEBUG] [WallTime: 1473631184.003397] [/ping_client/set_logger_level]: new Service instance
[INFO] [WallTime: 1473631184.130352] Waiting for ping action server...
[DEBUG] [WallTime: 1473631184.131371] connecting to raspberrypi 52197
[DEBUG] [WallTime: 1473631184.131768] connecting to raspberrypi 52197
[DEBUG] [WallTime: 1473631184.152471] connecting to raspberrypi 52197
[ERROR] [WallTime: 1473631194.139802] Ping action server timed out
[INFO] [WallTime: 1473631194.140166] Shutting down
[DEBUG] [WallTime: 1473631194.192350] connecting to raspberrypi 52197
[DEBUG] [WallTime: 1473631194.193241] connecting to raspberrypi 52197

Any ideas would be appreciated. If it matters, I have a ROS publisher that runs on the Ubuntu VM and a ROS Subscriber on the Raspberry Pi that successfully receives the published messages. The Raspberry Pi has a static IP and the Ubuntu VM has an entry in /etc/hosts to map the static IP to the host name "raspberrypi".

Here are the Ubuntu environment settings:

mike@badmonkey:~$ printenv | grep ROS
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Your hostname is badmonkey but your ROS_HOSTNAME is raspberrypi. Can you ping a node that is running on your Ubuntu machine from your raspberry pi?

ahendrix gravatar image ahendrix  ( 2016-09-11 21:19:06 -0500 )edit

No, rosnode list includes the node, but I get this...

pi@raspberrypi:~ $ rosnode ping leap_motion_publisher
rosnode: node is [/leap_motion_publisher]
pinging /leap_motion_publisher with a timeout of 3.0s
ERROR: connection refused to [http://raspberrypi:45057/]
anonymous userAnonymous ( 2016-09-12 18:20:46 -0500 )edit

Your hostname is badmonkey but your ROS_HOSTNAME is raspberrypi, so any nodes running on your Ubuntu machine are advertising the wrong host name.

ahendrix gravatar image ahendrix  ( 2016-09-12 20:43:35 -0500 )edit

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answered 2016-09-13 07:05:38 -0500

anonymous user


As @ahendrix pointed out in the question comments, I was confused about ROS_HOSTNAME. I had assumed that was the hostname of the node running roscore. When I changed the ROS_HOSTNAME to properly reflect the hostname of the Ubuntu VM to be badmonkey instead of raspberrypi, the problem was resolved.

Thank you for your help!

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Asked: 2016-09-11 17:12:08 -0500

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Last updated: Sep 13 '16