CODEWITHSUNDEEP
pythonsignalssigterm
akipro
akipro

Reputation: 188

Python: Override default SIGTERM handler

I am sending SIGTERM signal to my server via start-stop-daemon. As expected the server shuts down when signal is received. Now I want to halt my server for 10 sec after receiving SIGTERM and then shut it down. To achieve this I wrote

def sigterm_handler(signum):
    time.sleep(10)
    sys.exit(0)    

Class server(object):
    .
    .

    def __call__()
        signal.signal(signal.SIGTERM, sigterm_handler)
        #some code

    .
    .

Now the server never waits for 10 secs after receiving signal. As soon as the signal is send, it shuts down (checked in loggers).

Also the following message halts for 10 secs on my terminal. 

* Stopping Server:

I think my code is not able to tell python that the signal is being handled and so, the default handler is also being called along with my handler. Any idea what needs to be done?

Upvotes: 0

Views: 1290

Answers (1)

jofel
jofel

Reputation: 3405

The problem is your sigterm_handler. It blocks your server as soon as it recieves the SIGTERM for 10s and then shut it down.

What you really want is "ignoring" the signal and then exit the server after 10s (for example with another signal):

shutdown_mode=False

def alarm_handler(signum, frame):
        sys.exit(0)

def sigterm_handler(signum):
     global shutdown_mode
     if not shutdown_mode:
            shutdown_mode=True
            signal.signal(signal.SIGALRM, alarm_handler)
            signal.alarm(10)

You want also switch into a "shutdown mode", where e.g. the server should not accept new connections etc.

Upvotes: 1

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