subscriber and publisher show different situation with differet created way when they receive messages.

[fengmao31]

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Environment

• libzmq version (commit hash if unreleased): master
• OS: ubuntu20.04

Issue description

I find subscriber and publisher show different situation with differet created way when they receive messages. I test the different situation that zmq publisher use stack or heap, while zmq recevier use stack

Experiment

publisher

when I use stack to create zmq::context_t and zmq::socket_t, zmq subscriber lost first messages from zmq publisher.

when I use heap to create zmq::context_t and zmq::socket_t, zmq subscriber can get all messages from zmq publisher.

subscriber

[fengmao31]

It is because in a huge while. the stack variable is created and destroyed repeatly. while the zmq::context_t context and zmq::socket_t publisher is not in the while. only the make _unique operating in the while.

But why repeatly make _unique looks like not realloc the momery?