I am using over 20 raspberry pis to control heating and other functions in my house. For instance each room has a pi (client) with a temperature sensor, which sends a message to another pi (server) at one of three manifolds to open or close a valve on the heating system. My problem is the amount of time the server takes to execute the bind instruction. A newly set up pi will typically take a few millisecond to execute the line, but soon the time becomes variable, sometimes milliseconds, usually seconds, but frequently tens of seconds or even hundreds of seconds.
typical code,
elapselp = default_timer() # timing start
port = 12571 # port number, many different ones used
while bound == 0:
try:
s1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s1.bind(('', port))
bound = 1
elapselp1 = default_timer() - elapselp
print ('bind time = ', elapselp1)
As stated above elapselp1 can be at the low millisecond level, or 200 seconds which causes significant problems.
I usually find I can get back to short times by changing the port number used, which means changing on all the clients, but after some time running happily the times will increase again. Rebooting or powering down does not help. I am using Raspberry 4s and Zero Ws, no difference. I suspect that some register is not clearing, but outside that am clueless. Can somebody advise please. I am running Rasparian 3.6 and Python3
Thank you for all your replies, here is the remainder of this section of the code.
As I’m not sure how to input his I’m breaking it down over a number of comments.
elapselp = default_timer()
port =12571
while bound == 0:
try:
s1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s1.bind(('', port))
bound = 1
elapselp1 = default_timer()- elapselp
print (‘bind time = ‘, elapselp2)
except:
dummy = 1
s1.listen(5)
print ('waiting for input ', end='')
while True:
conn, addr = s1.accept()
print ('connected by ', addr)
conn.send('thank you'.encode())
data = conn.recv(1024).decode()
print ('data = ', data)
time.sleep(5)
conn.close()
s1.close()
if data == '10':
startdaw = default_timer()
GPIO.output(22, GPIO.LOW)
print ('switch dining area heating off')
h1 = 0
dawl = edaw
startdawr = default_timer()
elif data == '11':
GPIO.output(22, GPIO.HIGH)
## A lot of other actions depending on data received here
else:
print ('another code ', data)
if not data:
break
print ('yet another')
I have a number of Raspberry pi Zeros running the code for test along with 7 doing so as part of my control system. The performance is very erratic. One unit running through the code every 30 seconds in response to a client has been running over 5 days, majority of the bind times have been under 1 millsec, I see some between 1 and 10, but it has recorded one time of 130 seconds. Another unit which failed to bind for over two hours has now completed over 33,000 binds (this one just closes after the bind, no if statements), and the longest time for a bind is 710 msec.
If I take out the try/except I get no error message, it just drops through and loops back.
I hope there is some useful information in there.
