Mininetでstop()を実行した際にエラーが出力される。

#やりたいこと
ネットワークエミュレータMininetを使用し以下のようなダンベルトポロジーを構築したい。
h1----r1----r2----h2

#困っている点
Mininetでネットワークトポロジーを構築しiperfを実行するpythonコードを書きました。
以下にコードを示します。
また、コードの下に出力結果を示します。

出力結果を見ると、net.stop()の部分でエラーが出力されるようです。
そこで、エラーの原因と解消方法を教えてください。

python
1#!/usr/bin/python
2
3from mininet.topo import Topo
4from mininet.net import Mininet
5from mininet.node import CPULimitedHost
6from mininet.link import TCLink
7from mininet.util import dumpNodeConnections
8from mininet.log import setLogLevel
9from mininet.cli import CLI
10
11import time
12import subprocess
13import sys
14import threading
15import csv
16from argparse import ArgumentParser
17
18from time import sleep, time
19import re
20
21pid = None
22
23def get_option():
24    parser = ArgumentParser(description='explanation of program')
25
26    parser.add_argument('-c', '--cc', help="name of cc schemes", type=str, default='none')
27
28    return parser.parse_args()
29
30
31
32class SingleSwitchTopo(Topo):
33    "Single switch connected to n hosts."
34    def __init__(self, n=2, **opts):
35        Topo.__init__(self, **opts)
36        hosts=[]
37        routers=[]    
38
39        for h in range(2):
40            routers.append(self.addHost('h%s' % (h + 1)))
41        self.addLink(routers[0], routers[1], intfName1='r1-eth0', intfName2='r2-eth0',
42        bw=100, delay='5ms', loss=0,max_queue_size=79,use_tbf=True)
43
44        for h in range(n):
45            print(h)
46            # Each host gets 50%/n of system CPU
47            hosts.append(self.addHost('h%s' % str(2*(h + 1)-1)))
48            hosts.append(self.addHost('h%s' % str(2*(h + 1))))
49            # 10 Mbps, 5ms delay, 10% loss, 1000 packet queue
50            
51            self.addLink(hosts[2*(h)], routers[0], intfName1='h'+str(2*(h)+1)+'-eth0', intfName2='r1-eth'+str(h+1),
52                bw=200, delay='5ms', loss=0,max_queue_size=1000,use_tbf=True)
53            
54            self.addLink(hosts[2*(h)+1], routers[1], intfName1='h'+str(2*(h+1))+'-eth0', intfName2='r2-eth'+str(h+1),
55                bw=200, delay='5ms', loss=0,max_queue_size=1000,use_tbf=True)
56        
57
58 
59
60def monitor_qlen(node,interval_sec=0.1):
61    pat_queued =re.compile(r'backlog\s[^\s]+\s([\d]+)p')
62
63    cmd = "tc -s qdisc show dev h1-eth0"
64
65    ret = []
66    open("dump/qlen.csv","w").write('')
67    t0 = "%f" % time()
68
69    while 1: 
70        # p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
71        p = node.popen(cmd, shell=True, stdout=subprocess.PIPE)
72        output = p.stdout.read()
73
74        matches = pat_queued.findall(output)
75
76        if matches and len(matches) > 1:
77            ret.append(matches[1])
78            t1 = "%f" % time()
79            #print str(float(t1)-float(t0)), matches[1]
80            open("dump/qlen.csv","a").write(str(float(t1)-float(t0))+','+matches[1]+'\n')
81
82        sleep(interval_sec)
83
84def run_ccp():
85    global pid
86    pid = subprocess.Popen(['sudo', '/home/maeta/eval-scripts/generic-cong-avoid/target/release/cubic', '--ipc=netlink'],stdout=subprocess.PIPE,stderr = subprocess.STDOUT)
87    with open('dump/cwnd.csv', 'w') as f:
88        for line in iter(pid.stdout.readline, b''):
89            #print(line.rstrip().decode('utf8'))
90            output = (line.rstrip().decode('utf8').split(','))
91            output_str = [str(n) for n in output]
92            if (output_str[0].isdigit()):
93                writer = csv.writer(f)
94                writer.writerow(output_str)
95            sys.stdout.flush()
96
97
98def perfTest(cc):
99    global pid
100    "Create network and run simple performance test"
101    topo = SingleSwitchTopo(n=1)
102    net = Mininet(topo=topo, 
103                  host=CPULimitedHost, link=TCLink,controller=None)
104    h1, h2 = net.get('h1', 'h2')
105
106    #h1_tx = h1.cmd('ip l set dev h1-eth0 txqueue 1' )
107    #h2_tx = h2.cmd('ip l set dev h2-eth0 txqueue 1' )
108
109    net.start()    
110    #CLI(net)
111    h1_eth = h1.cmd('ethtool -K h1-eth0 tx off sg off tso off ufo off' )
112    h2_eth = h2.cmd('ethtool -K h2-eth0 tx off sg off tso off ufo off' )
113 
114    thread2 = threading.Thread(target=monitor_qlen, args=(h2,))
115    thread2.setDaemon(True)
116    thread2.start()
117
118    h1_dmp = h1.popen('tcpdump', '-x', '-tt', '-nn', '-Z', 'root', '-B', '1000', '-w', 'dump/receiver.pcap')
119    h2_dmp = h2.popen('tcpdump', '-x', '-tt', '-nn', '-Z', 'root', '-B', '1000', '-w', 'dump/sender.pcap')
120
121
122    h2_pid = h2.popen('iperf', '-s', '-p', '5001')
123    h1_pid = h1.popen(['iperf', '-c', h2.IP(), '-p', '5001', '-t', '5','-i', '1','-Z', args.cc],stdout=subprocess.PIPE,stderr = subprocess.STDOUT)
124    
125    try:
126        for line in iter(h1_pid.stdout.readline, b''):
127            print(line.rstrip().decode('utf8'))
128            sys.stdout.flush()
129    
130    finally:
131        h1_pid.kill()
132        h1_dmp.kill()
133        h2_pid.kill()
134        h2_dmp.kill()
135        if (cc == 'ccp'):
136            pid.kill()
137
138    net.stop()
139    
140
141if __name__ == '__main__':
142
143    args = get_option()
144    setLogLevel('info')
145    if (args.cc == 'ccp'):
146        thread1 = threading.Thread(target=run_ccp)
147        thread1.setDaemon(True)
148        thread1.start()
149
150    sleep(1)
151    perfTest(args.cc)
152    sys.exit()
153    # thread1.join()

*** Creating network
*** Adding hosts:
h1 h2 
*** Adding switches:

*** Adding links:
(200.00Mbit 5ms delay 0.00000% loss) (200.00Mbit 5ms delay 0.00000% loss) (h1, h1) (100.00Mbit 5ms delay 0.00000% loss) (100.00Mbit 5ms delay 0.00000% loss) (h1, h2) (200.00Mbit 5ms delay 0.00000% loss) (200.00Mbit 5ms delay 0.00000% loss) (h2, h2) 
*** Configuring hosts
h1 (cfs -1/100000us) h2 (cfs -1/100000us) 
*** Starting controller

*** Starting 0 switches

------------------------------------------------------------
Client connecting to 10.0.0.2, TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[  9] local 10.0.0.1 port 34624 connected with 10.0.0.2 port 5001
[ ID] Interval       Transfer     Bandwidth
[  9]  0.0- 1.0 sec  11.1 MBytes  93.3 Mbits/sec
[  9]  1.0- 2.0 sec  9.50 MBytes  79.7 Mbits/sec
[  9]  2.0- 3.0 sec  9.00 MBytes  75.5 Mbits/sec
[  9]  3.0- 4.0 sec  10.2 MBytes  86.0 Mbits/sec
[  9]  4.0- 5.0 sec  8.88 MBytes  74.4 Mbits/sec
[  9]  0.0- 5.1 sec  48.8 MBytes  80.9 Mbits/sec
*** Stopping 0 controllers

*** Stopping 3 links
.Traceback (most recent call last):
  File "dumbbell.py", line 151, in <module>
    perfTest(args.cc)
  File "dumbbell.py", line 138, in perfTest
    net.stop()
  File "/usr/local/lib/python2.7/dist-packages/mininet/net.py", line 581, in stop
    link.stop()
  File "/usr/local/lib/python2.7/dist-packages/mininet/link.py", line 513, in stop
    self.delete()
  File "/usr/local/lib/python2.7/dist-packages/mininet/link.py", line 508, in delete
    self.intf2.delete()
  File "/usr/local/lib/python2.7/dist-packages/mininet/link.py", line 213, in delete
    self.node.delIntf( self )
  File "/usr/local/lib/python2.7/dist-packages/mininet/node.py", line 471, in delIntf
    del self.intfs[ port ]
KeyError: 1