[ROS] 처리 지연 문제

topic을 처리할 때 시간이 걸리는데 그러면 바로 그 다음 topic를 처리하는지, 그때 들어온 topic을 처리하는지를 확인하기 위한 실습

1. sender

#!/usr/bin/env python

import rospy
from std_msgs.msg import Int32

name = "sender"
pub_topic = "my_topic"

rospy.init_node(name)
pub = rospy.Publisher(pub_topic, Int32, queue_size=1)

rate = rospy.Rate(1000)
count = 1

while(pub.get_num_connections()==0):
    continue

while not rospy.is_shutdown():
    pub.publish(count)
    count = count+1
    rate.sleep()

2. receiver

#!/usr/bin/env python

import rospy
from std_msgs.msg import Int32

name = "receiver"
sub_topic = "my_topic"

def callback(msg):
    rospy.loginfo("callback id being processed")
    rospy.sleep(5)
    print msg.data

rospy.init_node(name)
rospy.Subscriber(sub_topic, Int32, callback, queue_size=1)
rospy.spin()

3. launch

<launch>
    <node pkg="msg_send" type="sender_overflow.py" name="sender"/>
    <node pkg="msg_send" type="receiver_overflow.py" name="receiver" output="screen"/>
</launch>

4. chmod

$ chmod +x receiver_overflow.py sender_overflow.py

5. cm

6. 실행

$ roslaunch msg_send sr_overflow.launch