def recurs_mod_loop(pi,i) :
...
        node = conn_pipes[pi][i]        
        if node.workloop_in() >= 0 :
            if i < max_conn_pipes[pi] :
                recurs_mod_loop(pi,i+1)
...

while True :
...
            pi = 0
            while pi < len(conn_pipes):
                recurs_mod_loop(pi,0)
                pi += 1
...

import threading
import math
import time

def t1():
    for i in range(10):
        v=0
        for i in xrange(500000):
            v+=math.sin(i)
#        time.sleep(5)
        print "echo1"

th=threading.Thread(target=t1)
th.start()
for i in range(10):
    v=0
#    time.sleep(0)
    a=input()
    print "echo0"
th.join()