Memory Issue

[luckyluke98]

Hi,
I'm having a memory problem, I'm simulating the BB84 + Cascade protocol on various pairs of QKD nodes. I start a simulation of 1 second and the various couples begin to exchange keys, unfortunately I notice that the simulation consumes an enormous amount of memory, in fact for 1 second of simulation it consumes around 12 GB. Since I checked if the problem was mine but it isn't (I don't have objects that fill and don't empty) I think it's very likely that there is a memory leak in the implementation of the Cascade or BB84 protocol.

I hope I explained myself.

Thank you

Luca

[luckyluke98]

Hi, I'll try to be more explicit. I'll simplify with an example that I found on the "tests/qkd/test_cascade.py" folder, which I modified slightly.

The simulation occupies 4.7 GB of RAM, for a simulation on two QKD Nodes.

Luca

class Parent(StackProtocol):
    def __init__(self, own: "Node", keysize: int, keynum: int):
        super().__init__(own, "")
        self.upper_protocols = []
        self.lower_protocols = []
        self.keysize = keysize
        self.keynum = keynum
        self.keys = []
        self.counter = 0

    def init(self):
        pass

    def pop(self, key):
        self.keys.append(key)
        self.counter += 1

    def push(self):
        self.lower_protocols[0].push(self.keysize, self.keynum)

    def received_message(self):
        pass


def test_cascade_run():
    KEYSIZE = 128
    KEYNUM = math.inf

    tl = Timeline(1e12)

    ls_arg = {"LightSource" : 
                        {
                            "mean_photon_num" : 1
                        }
                    }

    alice = QKDNode("alice", tl, component_templates = ls_arg)
    bob = QKDNode("bob", tl)
    alice.set_seed(0)
    bob.set_seed(0)
    pair_bb84_protocols(alice.protocol_stack[0], bob.protocol_stack[0])
    pair_cascade_protocols(alice.protocol_stack[1], bob.protocol_stack[1])

    qc0 = QuantumChannel("qc0", tl, distance=1e3, attenuation=0.00000,
                         polarization_fidelity=1)
    qc1 = QuantumChannel("qc1", tl, distance=1e3, attenuation=0.00000,
                         polarization_fidelity=1)
    
    qc0.set_ends(alice, bob.name)
    qc1.set_ends(bob, alice.name)
    cc0 = ClassicalChannel("cc0", tl, distance=1e3)
    cc1 = ClassicalChannel("cc1", tl, distance=1e3)
    cc0.set_ends(alice, bob.name)
    cc1.set_ends(bob, alice.name)

    # Parent
    pa = Parent(alice, KEYSIZE, KEYNUM)
    pb = Parent(bob, KEYSIZE, KEYNUM)
    alice.protocol_stack[1].upper_protocols.append(pa)
    pa.lower_protocols.append(alice.protocol_stack[1])
    bob.protocol_stack[1].upper_protocols.append(pb)
    pb.lower_protocols.append(bob.protocol_stack[1])

    process = Process(pa, "push", [])
    event = Event(0, process)
    tl.schedule(event)

    tl.init()
    tl.run()