Why are LINGER = 0 and SNDTIMEO = 0 used for PAIR jacks of Zyre artists?

Question

Having studied the source code of Pyre (Python version of Zyre), I saw the following:

def zcreate_pipe(ctx, hwm=1000):
    backend = zsocket.ZSocket(ctx, zmq.PAIR)
    frontend = zsocket.ZSocket(ctx, zmq.PAIR)
    # ...
    # close immediately on shutdown
    backend.setsockopt(zmq.LINGER, 0)
    frontend.setsockopt(zmq.LINGER, 0)

class ZActor(object):
    # ...

    def __init__(self, ctx, actor, *args, **kwargs):
        # ...
        self.pipe, self.shim_pipe = zhelper.zcreate_pipe(ctx)
        # ...

    def run(self):
        self.shim_handler(*self.shim_args, **self.shim_kwargs)
        self.shim_pipe.set(zmq.SNDTIMEO, 0)
        self.shim_pipe.signal()
        self.shim_pipe.close()

    def destroy(self):
        # ...
        self.pipe.set(zmq.SNDTIMEO, 0)
        self.pipe.send_unicode("$TERM")
        self.pipe.wait()
        self.pipe.close()

Interesting for me was the use of LINGER=0and SNDTIMEO=0.

Relevant documents here and here :

ZMQ_SNDTIMEO: Maximum time before a send operation returns with EAGAIN

[pretty self-evident]

ZMQ_LINGER: set the delay period for disconnecting a socket

[...] The delay period determines how long waiting messages that have not yet been sent to the peer will be delayed in memory after the socket is closed with zmq_close (3) and will additionally affect the completion of the socket context with zmq_term (3 ) [...]

• [...]

• 0 . , zmq_close().

• [...]

, . send , SNDTIMEO=0, (, -) LINGER=0 close.

, $TERM , , signal , . , , - (- PAIR over inproc:// transport?), ?

, , / ?

Answer 1

(/) . , , ( "hwm" ) - , zmq , destroy() , "$ TERM", - recv() -, .

[ , wait() destroy(), , .

destroy() - , , - , send destroy(), - ( ) wait().