HWM not reliable

[fbacchella]

hwm don't seems to be reliable on open socket.

I tried the following code:

    import java.util.Date;
    import java.util.function.Consumer;

    import org.zeromq.ZMQ;
    import org.zeromq.ZMQ.Context;
    import org.zeromq.ZMQ.Socket;

    public class TestOne {

        static public void main(final String[] args) throws InterruptedException {
            Context context = ZMQ.context(1);
            Socket spull = context.socket(ZMQ.PULL);
            spull.setRcvHWM(1);
            spull.bind("ipc://one");
            Socket spush = context.socket(ZMQ.PUSH);
            spush.setSndHWM(5);
            spush.setSendTimeOut(100);
            spush.connect("ipc://one");
            long timestart = (new Date()).getTime();
            Consumer<Object> delta= (i) -> { System.out.println("" + Long.toString((new Date()).getTime() - timestart) + ": " + i.toString());};
            for(int i = 1; i < 20; i++) {
                delta.accept("" + i+ " " + spush.send("" + i) + " " + spush.base().errno());
                Thread.sleep(1);
            }
            delta.accept("" + new String(spull.recv()));
        }
    }

I'm not getting reliable results.

It should hang after 5 ou 6 events or failed. But spush.send("" + i) always succeed. And errno is not always consistent. Some time this code output:

    55: 1 true 0
    57: 2 true 0
    58: 3 true 0
    60: 4 true 0
    61: 5 true 0
    63: 6 true 35
    64: 7 true 35
    66: 8 true 35
    67: 9 true 35
    68: 10 true 35
    70: 11 true 35
    71: 12 true 35
    73: 13 true 35
    74: 14 true 35
    75: 15 true 35
    77: 16 true 35
    78: 17 true 35
    79: 18 true 35
    81: 19 true 35
    82: 1

How can I get a true (send succeed) but still get a 35 errno ? But I can also get:

    55: 1 true 0
    58: 2 true 0
    60: 3 true 0
    61: 4 true 0
    63: 5 true 0
    64: 6 true 0
    65: 7 true 0
    67: 8 true 0
    68: 9 true 0
    69: 10 true 0
    71: 11 true 0
    72: 12 true 0
    74: 13 true 0
    75: 14 true 0
    76: 15 true 0
    78: 16 true 0
    79: 17 true 0
    81: 18 true 0
    82: 19 true 0
    84: 1

I tried it with a git clone of the day.

If there is no pull socket open, I get the expected results:

    60: 1 true 0
    62: 2 true 0
    63: 3 true 0
    65: 4 true 0
    66: 5 true 0
    172: 6 false 35
    278: 7 false 35
    384: 8 false 35
    486: 9 false 35
    592: 10 false 35
    696: 11 false 35
    802: 12 false 35
    904: 13 false 35
    1009: 14 false 35
    1114: 15 false 35
    1220: 16 false 35
    1325: 17 false 35
    1428: 18 false 35
    1533: 19 false 35

[Deltatiger]

Recently found that this issue still exists. Neither HWM or buffer size seems to work correctly.

[fredoboulo]

It is only for inproc transport that the number of messages able to be sent without hanging is equal to send HWM + receive HWM. As it is ipc transport, the mechanism is very different.

I invite you to read https://github.com/zeromq/pyzmq/issues/96, comments are especially insightful.

Regarding errno, value should be considered only in case of error, as it is not automatically reset between calls.