I'm using zmq on a computer (python) to communicate with a robot (c++) using zmq.
The communication works most of the time but is then interrupted by an interrupted system call error after some time (no exact point in time).
Python: to connect
self.context = zmq.Context()
self.stateSocket = self.context.socket(zmq.REQ)
self.failCounter = 0
self.poll = zmq.Poller()
try:
self.stateSocket = self.context.socket(zmq.REQ)
self.stateSocket.connect(self.connectString)
self.poll.register(self.stateSocket, zmq.POLLIN)
self.timer.start()
except zmq.ZMQError as e:
print("Connection to socket not possible: ", e)
to communicate looping in a QTTimer:
retries_left = 2
while retries_left:
request = #data here
self.stateSocket.send_string(request, zmq.NOBLOCK)
expect_reply = True
while expect_reply:
socks = dict(self.poll.poll(400))
if socks.get(self.stateSocket) == zmq.POLLIN:
message = self.stateSocket.recv()
if not message:
break
expect_reply = False
retries_left = 0
self.receivedValues = [float(i) for i in message.decode("UTF-8").split(',')]
self.dataAnalysis() #do stuff with received values
else:
print("W: No response from server, retrying ...")
# Socket is confused. Close and remove it.
self.stateSocket.setsockopt(zmq.LINGER, 0)
self.stateSocket.close()
self.poll.unregister(self.stateSocket)
retries_left -= 1
if retries_left == 0:
print("E: Server seems to be offline, abandoning")
break
else:
print("I: Reconnecting and resending ")
# Create new connection
self.stateSocket = self.context.socket(zmq.REQ)
self.stateSocket.connect(self.connectString)
self.poll.register(self.stateSocket, zmq.POLLIN)
self.stateSocket.send_string(request)
and the cpp part:
//setup
zmq::context_t context{ 1 };
zmq::socket_t socket{ context, ZMQ_REP };
const std::chrono::milliseconds timeout{ 400 };
zmq::pollitem_t pollItem[1];
zmq::message_t receivedData;
try
{
int rc = zmq::poll(pollItem, 1, 400);
if (rc < 0)
{
std::cout << "No data available" << std::endl;
}
else
{
socket.recv(receivedData, zmq::recv_flags::dontwait);
}
zmq::message_t reply{ replyString.cbegin(), replyString.cend() };
socket.send(reply, zmq::send_flags::dontwait);
}
catch (zmq::error_t& e)
{
std::cout << "Sending Error: " << e.what() << std::endl;
}
This runs for 30+ seconds and then the cpp part throws an Interrupted system call error. From what I have read this means something is blocking but I can't figure out what might be the issue.
Can anyone figure out what I'm doing wrong?
