How to create a ROS node that can start and stop counting based on what message the other node its subscribed to sends

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Hello, I am basically trying to get a node that both publishes and subscribes. Imagine I have two nodes, node1 publishes and count_node subscribes and publishes as well. When node1 publishes "start count" I want count_node to start counting and publish the count value. If node1 publishes to "stop count" while count_node is counting, I want count_node to stop the active count. My attempt is below in code. I use ROS Melodic on Ubuntu 18.04

My attempt thus far fails because when I receive the message to start the count the callback function calls a function (startCount) that uses a while loop to increment. Thus until the count it finished, count_node cannot process the message to stop the count and the stopCount function is called AFTER the count is finished, not while its counting.

Is there a way to do what I want?

Here is my attempt at count_node:

import rospy
from std_msgs.msg import String
from std_msgs.msg import Int32

def callback(data):
    rospy.loginfo(rospy.get_caller_id() + ' I heard: %s', data.data)
    if (data.data=="start count"):
        startSanitization()        
    elif (data.data=="stop count"):
        stopSanitization()

def startCount():
    percent = 0

    while percent < 101 :
        rospy.loginfo(percent)
        pub.publish(percent)
        percent = percent + 1
        rate.sleep()     

def stopCount():
    percent = 0
    rospy.loginfo(percent)
    pub.publish(percent)

def listener():

    # In ROS, nodes are uniquely named. If two nodes with the same
    # name are launched, the previous one is kicked off. The
    # anonymous=True flag means that rospy will choose a unique
    # name for our 'listener' node so that multiple listeners can
    # run simultaneously.

    #check for message on Topic
    rospy.Subscriber('brwsrButtons', String, callback)

    rospy.loginfo("hello")
    # spin() simply keeps python from exiting until this node is stopped
    rospy.spin()

if __name__ == '__main__':
    #create a unique node
    rospy.init_node('count_node', anonymous=True)
    #create a publisher object
    pub = rospy.Publisher('progress', Int32, queue_size=10)
    rate = rospy.Rate(10) #10Hz
    #start the subscribing and publishing process
    listener()

*New Updated code:

import rospy
from std_msgs.msg import String
from std_msgs.msg import Int32
from multiprocessing import Process, Pipe
import thread

keepCounting = 0
percent = 0

def callback(data,keepCounting):
#    rospy.loginfo(rospy.get_caller_id() + ' I heard: %s', data.data)

    if (data.data=="Started Sanitizing the Room"):
        rospy.loginfo(rospy.get_caller_id() + ' I heard: %s', data.data)
        keepCounting = 1
    elif (data.data=="Stopped Sanitizing the Room"):
        keepCounting = 0


def countingProc(percent, keepCounting):

    while percent < 101 and keepCounting==0 :
        rospy.loginfo(percent)
        pub.publish(percent)
        percent += 1
        rate.sleep()
#    elif keepCounting==0 :




def listener(percent, keepCounting):

    # In ROS, nodes are uniquely named. If two nodes with the same
    # name are launched, the previous one is kicked off. The
    # anonymous=True flag means that rospy will choose a unique
    # name for our 'listener' node so that multiple listeners can
    # run simultaneously.
    #check for message on Topic
    rospy.Subscriber('brwsrButtons', String, callback,(keepCounting))
    rospy.loginfo("hello")
    thread.start_new_thread (countingProc, (percent, keepCounting,))
    # spin() simply keeps python from exiting until this node is stopped
    rospy.spin()

if __name__ == '__main__':
    #create a unique node
    rospy ...