Changes in PyZMQ

This is a coarse summary of changes in pyzmq versions. For a real changelog, consult the git log

2.2.0.1

This is a tech-preview release, to try out some new features. It is expected to be short-lived, as there are likely to be issues to iron out, particularly with the new pip-install support.

Experimental New Stuff

These features are marked ‘experimental’, which means that their APIs are not set in stone, and may be removed or changed in incompatible ways in later releases.

Threadsafe ZMQStream

With the IOLoop inherited from tornado, there is exactly one method that is threadsafe: IOLoop.add_callback(). With this release, we are trying an experimental option to pass all IOLoop calls via this method, so that ZMQStreams can be used from one thread while the IOLoop runs in another. To try out a threadsafe stream:

stream = ZMQStream(socket, threadsafe=True)

pip install pyzmq

PyZMQ should now be pip installable, even on systems without libzmq. In these cases, when pyzmq fails to find an appropriate libzmq to link against, it will try to build libzmq as a Python extension. This work is derived from pyzmq_static.

To this end, PyZMQ source distributions include the sources for libzmq (2.2.0) and libuuid (2.21), both used under the LGPL.

zmq.green

The excellent gevent_zeromq socket subclass which provides gevent compatibility has been merged as zmq.green.

See also

gevent

Bugs fixed

• TIMEO sockopts are properly included for libzmq-2.2.0
• avoid garbage collection of sockets after fork (would cause assert (mailbox.cpp:79)).

2.2.0

Some effort has gone into refining the pyzmq API in this release to make it a model for other language bindings. This is principally made in a few renames of objects and methods, all of which leave the old name for backwards compatibility.

Note

As of this release, all code outside zmq.core is BSD licensed (where possible), to allow more permissive use of less-critical code and utilities.

Name Changes

• The Message class has been renamed to Frame, to better match other zmq bindings. The old Message name remains for backwards-compatibility. Wherever pyzmq docs say “Message”, they should refer to a complete zmq atom of communication (one or more Frames, connected by ZMQ_SNDMORE). Please report any remaining instances of Message==MessagePart with an Issue (or better yet a Pull Request).
• All foo_unicode methods are now called foo_string (_unicode remains for backwards compatibility). This is not only for cross-language consistency, but it makes more sense in Python 3, where native strings are unicode, and the _unicode suffix was wedded too much to Python 2.

Other Changes and Removals

• prefix removed as an unused keyword argument from send_multipart().
• ZMQStream send() default has been changed to copy=True, so it matches Socket send().
• ZMQStream on_err() is deprecated, because it never did anything.
• Python 2.5 compatibility has been dropped, and some code has been cleaned up to reflect no-longer-needed hacks.
• Some Cython files in zmq.core have been split, to reduce the amount of Cython-compiled code. Much of the body of these files were pure Python, and thus did not benefit from the increased compile time. This change also aims to ease maintaining feature parity in other projects, such as pyzmq-ctypes.

New Stuff

• Context objects can now set default options when they create a socket. These are set and accessed as attributes to the context. Socket options that do not apply to a socket (e.g. SUBSCRIBE on non-SUB sockets) will simply be ignored.
• on_recv_stream() has been added, which adds the stream itself as a second argument to the callback, making it easier to use a single callback on multiple streams.
• A more boolean attribute has been added to the Frame (née Message) class, so that frames can be identified as terminal without extra queires of rcvmore.

Experimental New Stuff

These features are marked ‘experimental’, which means that their APIs are not set in stone, and may be removed or changed in incompatible ways in later releases.

• zmq.web added for load-balancing requests in a tornado webapp with zeromq.

2.1.11

• remove support for LABEL prefixes. A major feature of libzmq-3.0, the LABEL prefix, has been removed from libzmq, prior to the first stable libzmq 3.x release.

  • The prefix argument to send_multipart() remains, but it continue to behave in exactly the same way as it always has on 2.1.x, simply prepending message parts.
  • recv_multipart() will always return a list, because prefixes are once again indistinguishable from regular message parts.

• add Socket.poll() method, for simple polling of events on a single socket.

• no longer require monkeypatching tornado IOLoop. The ioloop.ZMQPoller class is a poller implementation that matches tornado’s expectations, and pyzmq sockets can be used with any tornado application just by specifying the use of this poller. The pyzmq IOLoop implementation now only trivially differs from tornado’s.

  It is still recommended to use ioloop.install(), which sets both the zmq and tornado global IOLoop instances to the same object, but it is no longer necessary.

  Warning

  The most important part of this change is that the IOLoop.READ/WRITE/ERROR constants now match tornado’s, rather than being mapped directly to the zmq POLLIN/OUT/ERR. So applications that used the low-level IOLoop.add_handler() code with POLLIN/OUT/ERR directly (used to work, but was incorrect), rather than using the IOLoop class constants will no longer work. Fixing these to use the IOLoop constants should be insensitive to the actual value of the constants.

2.1.10

• Add support for libzmq-3.0 LABEL prefixes:

  Warning

  This feature has been removed from libzmq, and thus removed from future pyzmq as well.

  • send a message with label-prefix with:

    send_multipart([b'msg', b'parts'], prefix=[b'label', b'prefix'])
    

  • recv_multipart() returns a tuple of (prefix,msg) if a label prefix is detected

  • ZMQStreams and devices also respect the LABEL prefix

• add czmq-style close&term as ctx.destroy(), so that ctx.term() remains threadsafe and 1:1 with libzmq.

• Socket.close() takes optional linger option, for setting linger prior to closing.

• add zmq_version_info() and pyzmq_version_info() for getting libzmq and pyzmq versions as tuples of numbers. This helps with the fact that version string comparison breaks down once versions get into double-digits.

• ioloop changes merged from upstream Tornado 2.1

2.1.9

• added zmq.ssh tools for tunneling socket connections, copied from IPython
• Expanded sockopt support to cover changes in libzmq-4.0 dev.
• Fixed an issue that prevented KeyboardInterrupts from being catchable.
• Added attribute-access for set/getsockopt. Setting/Getting attributes of Sockets with the names of socket options is mapped to calls of set/getsockopt.

s.hwm = 10
s.identity = b'whoda'
s.linger
# -1

• Terminating a Context closes the sockets it created, matching the behavior in czmq.
• ThreadDevices use Context.instance() to create sockets, so they can use inproc connections to sockets in other threads.
• fixed units error on zmq.select(), where the poll timeout was 1000 times longer than expected.
• Add missing DEALER/ROUTER socket type names (currently aliases, to be replacements for XREP/XREQ).
• base libzmq dependency raised to 2.1.4 (first stable release) from 2.1.0.

2.1.7.1

• bdist for 64b Windows only. This fixed a type mismatch on the ZMQ_FD sockopt that only affected that platform.

2.1.7

• Added experimental support for libzmq-3.0 API
• Add zmq.eventloop.ioloop.install() for using pyzmq’s IOLoop in a tornado application.

2.1.4

• First version with binary distribution support
• Added instance() method for using a single Context throughout an application without passing references around.