Hope more detailed hint when "Address already in use" error happens in bind or connect

I use zmq a lot in my project, with many processings and many ports. Sometimes I don't close my program completely, and when I reopen my program, "Address already in use" error would happen, but because I store all ports in a dict, e.g.,

skt.bind(f"tcp://*:{port_dict['port_A']}")

In this situation, it is very hard to know which port is in use even there is traceback. So I have to

try:
    skt.bind(addr)
except zmq.error.ZMQError as e:
    raise RuntimeError(f"Failed to bind to {addr} because of {str(e)}")

or I must lsof -i and traverse every possible port.

But as I need to write like this in every bind/connect place, it is very verbose. So I think, if it is good to modify bind and connect in zmq/sugar/socket.py > Socket like this way:

class Socket(SocketBase, AttributeSetter):
    def bind(self, addr):
        try:
            super().bind(addr)
            ret = self._bind_cm(addr)
        except Exception as e:
            raise RuntimeError(f"Failed to bind to {addr} because of {str(e)}")
        return ret

    def connect(self, addr):
        try:
            super().connect(addr)
            ret = self._connect_cm(addr)
        except Exception as e:
            raise RuntimeError(f"Failed to connect to {addr} because of {str(e)}")
        return ret

Errors like FIleNotFound that don't specify the file that wasn't found always bother me! So this makes perfect sense. Other than the fact that it should be a ZMQError preserving the errno (i.e. change only the message, no other properties of the exception raised).

Errors like FIleNotFound that don't specify the file that wasn't found always bother me! So this makes perfect sense. Other than the fact that it should be a ZMQError preserving the errno (i.e. change only the message, no other properties of the exception raised).

Thank you for your kind reply! So what if

class Socket(SocketBase, AttributeSetter):
    def bind(self, addr):
        try:
            super().bind(addr)
            ret = self._bind_cm(addr)
        except Exception as e:
            raise type(e)(f"Failed to bind to {addr}"
                f" because of {str(e)}") from e
        return ret

like this?

I have tried to modify it both on win10 and ubuntu 22.04(wsl2), and the result output is

# win10
In [1]: import zmq

In [2]: ctx = zmq.Context()

In [3]: skt1 = ctx.socket(zmq.REP)

In [4]: skt1.bind("tcp://*:9999")
Out[4]: <SocketContext(bind='tcp://*:9999')>

In [5]: skt2 = ctx.socket(zmq.REP)

In [6]: skt2.bind("tcp://*:9999")
---------------------------------------------------------------------------
ZMQError                                  Traceback (most recent call last)
File ~\AppData\Local\Programs\Python\Python310\lib\site-packages\zmq\sugar\socket.py:215, in Socket.bind(self, addr)
    214 try:
--> 215     super().bind(addr)
    216     ret = self._bind_cm(addr)

File zmq\backend\cython\socket.pyx:540, in zmq.backend.cython.socket.Socket.bind()

File ~\AppData\Local\Programs\Python\Python310\lib\site-packages\zmq\backend\cython\checkrc.pxd:28, in zmq.backend.cython.checkrc._check_rc()

ZMQError: Address in use

The above exception was the direct cause of the following exception:

ZMQError                                  Traceback (most recent call last)
Cell In [6], line 1
----> 1 skt2.bind("tcp://*:9999")

File ~\AppData\Local\Programs\Python\Python310\lib\site-packages\zmq\sugar\socket.py:218, in Socket.bind(self, addr)
    216     ret = self._bind_cm(addr)
    217 except Exception as e:
--> 218     raise type(e)(f"Failed to bind to {addr}"
    219         f" because of {str(e)}") from e
    220 return ret

ZMQError: Failed to bind to tcp://*:9999 because of Address in use

#ubuntu 22.04(wsl2)
In [1]: import zmq

In [2]: ctx = zmq.Context()

In [3]: skt1 = ctx.socket(zmq.REP)

In [4]: skt1.bind("tcp://*:9999")
Out[4]: <SocketContext(bind='tcp://*:9999')>

In [5]: skt2 = ctx.socket(zmq.REP)

In [6]: skt2.bind("tcp://*:9999")
---------------------------------------------------------------------------
ZMQError                                  Traceback (most recent call last)
File ~/.local/lib/python3.10/site-packages/zmq/sugar/socket.py:302, in Socket.bind(self, addr)
    301 try:
--> 302     super().bind(addr)
    303     ret = self._bind_cm(addr)

File zmq/backend/cython/socket.pyx:564, in zmq.backend.cython.socket.Socket.bind()

File ~/.local/lib/python3.10/site-packages/zmq/backend/cython/checkrc.pxd:28, in zmq.backend.cython.checkrc._check_rc()

ZMQError: Address already in use

The above exception was the direct cause of the following exception:

ZMQError                                  Traceback (most recent call last)
Cell In[6], line 1
----> 1 skt2.bind("tcp://*:9999")

File ~/.local/lib/python3.10/site-packages/zmq/sugar/socket.py:305, in Socket.bind(self, addr)
    303     ret = self._bind_cm(addr)
    304 except Exception as e:
--> 305     raise type(e)(f"Failed to bind to {addr}"
    306         f" because of {str(e)}") from e
    307 return ret

ZMQError: Failed to bind to tcp://*:9999 because of Address already in use

I think maybe even simpler: append to the existing exception object's message attribute and then re-raise it instead of instantiating a new instance.

I think maybe even simpler: append to the existing exception object's message attribute and then re-raise it instead of instantiating a new instance.

I see. So maybe I need to modify socket.pyx

    def bind(self, addr):
        cdef int rc
        cdef char* c_addr

        _check_closed(self)
        addr_b = addr
        if isinstance(addr, str):
            addr_b = addr.encode('utf-8')
        elif isinstance(addr_b, bytes):
            addr = addr_b.decode('utf-8')

        if not isinstance(addr_b, bytes):
            raise TypeError('expected str, got: %r' % addr)
        c_addr = addr_b
        rc = zmq_bind(self.handle, c_addr)
        if rc != 0:
            if IPC_PATH_MAX_LEN and zmq_errno() == ENAMETOOLONG:
                path = addr.split('://', 1)[-1]
                msg = ('ipc path "{0}" is longer than {1} '
                                'characters (sizeof(sockaddr_un.sun_path)). '
                                'zmq.IPC_PATH_MAX_LEN constant can be used '
                                'to check addr length (if it is defined).'
                                .format(path, IPC_PATH_MAX_LEN))
                raise ZMQError(msg=msg)
            elif zmq_errno() == ENOENT:
                path = addr.split('://', 1)[-1]
                msg = ('No such file or directory for ipc path "{0}".'.format(
                       path))
                raise ZMQError(msg=msg)
            elif zmq_errno() == EADDRINUSE:  # which I add
                path = addr.split('://', 1)[-1]
                msg = 'Address in use for ipc path "{0}".'.format(path)
                raise ZMQError(msg=msg)
        while True:
            try:
                _check_rc(rc)
            except InterruptedSystemCall:
                rc = zmq_bind(self.handle, c_addr)
                continue
            else:
                break

but after python setup.py build_ext, I failed to import with hint ImportError: cannot import name '_device' from partially initialized module 'zmq.backend.cython' (most likely due to a circular import) (C:\pyzmq\zmq\backend\cython\__init__.py)

I don't have enough time to deal with it now, I'll try to test it in the near future.

I think you were right to put it in zmq.sugar.socket. I would do the very simplest thing and append to the strerror attribute of the ZMQError and re-raise it:

...
except ZMQError as e:
    # add address to the error message before raising
    e.strerror += f" (addr={addr!r})"
    raise

The spurious circular import message (I don't understand why Python thinks that's a good hint, but it's wrong) is likely caused by missing Cython files. You can do a full dev install with:

pip install -e .

@minrk Hello, sorry for late reply. I have solved the problem (I tried python setup.py build_ext without --inplace so it failed) and tested my code above on win10, and the result is

# win10
In [1]: import zmq

In [2]: ctx = zmq.Context()

In [3]: skt1 = ctx.socket(zmq.REP)

In [4]: skt1.bind("tcp://*:9999")
Out[4]: <SocketContext(bind='tcp://*:9999')>

In [5]: skt2 = ctx.socket(zmq.REP)

In [6]: skt2.bind("tcp://*:9999")
---------------------------------------------------------------------------
ZMQError                                  Traceback (most recent call last)
Cell In [6], line 1
----> 1 skt2.bind("tcp://*:9999")

File C:\Project\git\pyzmq\zmq\sugar\socket.py:301, in Socket.bind(self, addr)
    278 def bind(self: T, addr: str) -> _SocketContext[T]:
    279     """s.bind(addr)
    280
    281     Bind the socket to an address.
   (...)
    299
    300     """
--> 301     super().bind(addr)
    302     return self._bind_cm(addr)

File C:\Project\git\pyzmq\zmq\backend\cython\socket.pyx:565, in zmq.backend.cython.socket.Socket.bind()
    563         path = addr.split('://', 1)[-1]
    564         msg = 'Address in use for ipc path "{0}".'.format(path)
--> 565         raise ZMQError(msg=msg)
    566 while True:
    567     try:

ZMQError: Address in use for ipc path "*:9999".

I tried your code above, and that's really simple and we can get what we want by your code.

---------------------------------------------------------------------------
ZMQError                                  Traceback (most recent call last)
Cell In [6], line 1
----> 1 skt2.bind("tcp://*:9999")

File ~\AppData\Local\Programs\Python\Python310\lib\site-packages\zmq\sugar\socket.py:302, in Socket.bind(self, addr)
    279 """s.bind(addr)
    280
    281 Bind the socket to an address.
   (...)
    299
    300 """
    301 try:
--> 302     super().bind(addr)
    303     return self._bind_cm(addr)
    304 except ZMQError as e:
    305     # add address to the error message before raising

File zmq\backend\cython\socket.pyx:564, in zmq.backend.cython.socket.Socket.bind()

File ~\AppData\Local\Programs\Python\Python310\lib\site-packages\zmq\backend\cython\checkrc.pxd:28, in zmq.backend.cython.checkrc._check_rc()

ZMQError: Address in use (addr='tcp://*:9999')

I didn't know this way before, so thank you for making me know that. And I think you should push your code if you think this issue is worth to merge.

zeromq / pyzmq

Hope more detailed hint when "Address already in use" error happens in bind or connect #1862