Detailed information on what has changed is available in the Changelog. This document summarizes the most important changes since gevent 1.2.
gevent 1.3 is an important update for performance, debugging and monitoring, and platform support. It introduces an (optional) libuv loop implementation and supports PyPy on Windows. See Event Loop Implementations: libuv and libev for more.
Since gevent 1.2.2 there have been about 450 commits from a half-dozen contributors. Almost 100 pull requests and more than 100 issues have been closed.
gevent 1.3 supports Python 2.7, 3.4, 3.5, 3.6 and 3.7 on the CPython (python.org) interpreter. It also supports PyPy2 5.8.0 and above (PyPy2 5.10 or higher is recommended) and PyPy3 5.10.0.
Caution
Python 2.7.8 and below (Python 2.7 without a modern
ssl module), is no longer tested or supported. The
support code remains in this release and gevent can be
installed on such implementations, but such usage is not
supported. Support for Python 2.7.8 will be removed in the next
major version of gevent.
Note
PyPy is now supported on Windows with the libuv loop implementation.
Python 3.7 is in the process of release right now and gevent is tested with 3.7b4, the last scheduled beta for Python 3.7.
For ease of installation on Windows, OS X and Linux, gevent 1.3 is distributed as pre-compiled binary wheels, in addition to source code.
Note
On Linux, you’ll need to install gevent from source if you wish to use the libuv loop implementation. This is because the manylinux1 specification for the distributed wheels does not support libuv. The CFFI library must be installed at build time.
Greenlet objects have gained some useful new
attributes:
Greenlet.spawning_greenlet is the greenlet that created this
greenlet. Since the parent of a greenlet is almost always gevent’s
hub, this can be more
useful to understand greenlet relationships.
Greenlet.spawn_tree_locals is a dictionary of values
maintained through the spawn tree (i.e., all descendents of a
particular greenlet based on spawning_greenlet). This is
convenient to share values between a set of greenlets, for example,
all those involved in processing a request.
Greenlet.spawning_stack is a frame -like object that
captures where the greenlet was created and can be passed to traceback.print_stack().
Greenlet.minimal_ident is a small integer unique across all
greenlets.
Greenlet.name is a string printed in the greenlet’s repr by default.
“Raw” greenlets created with spawn_raw default to having the
spawning_greenlet and spawn_tree_locals.
This extra data is printed by the new
gevent.util.print_run_info() function.
gevent 1.3 uses Cython on CPython to compile several performance
critical modules. As a result, overall performance is improved.
Specifically, queues are up to 5 times faster, pools are 10-20%
faster, and the gevent.local.local is up to 40 times faster.
See pull request #1156, pull request #1155, pull request #1117 and pull request #1154.
In gevent 1.2.2, event loop callbacks (including things like
sleep(0)) would be run in sequence until we ran them all, or until
we ran 10,000. Simply counting the number of callbacks could lead to
no IO being serviced for an arbitrary, unbound, amount of time. To
correct this, gevent 1.3 introduces gevent.getswitchinterval and
will run callbacks for only (approximately) that amount of time before
checking for IO. (This is similar to the way that Python 2 counted
bytecode instructions between thread switches but Python 3 uses the
more deterministic timer approach.) The hope is that this will result
in “smoother” application behaviour and fewer pitfalls. See
issue #1072 for more details.
Many of the new greenlet attributes are useful for monitoring and debugging gevent applications. gevent also now has the (optional) ability to monitor for greenlets that call blocking functions and stall the event loop and to periodically check if the application has exceeded a configured memory limit. See Monitoring and Debugging gevent Applications for more information.
The dnspython library is a new, pure-Python option for Name Resolution (DNS). Benchmarks show it to be faster than the existing c-ares resolver and it is also more stable on PyPy. The c-ares resolver may be deprecated and removed in the future.
Numerous APIs offer slightly expanded functionality in this version. Look for “changed in version 1.3” or “added in version 1.3” throughout the documentation for specifics.
A few changes of note:
The low-level watcher objects now have a
close() method that must be
called to promptly dispose of native (libev or libuv) resources.
gevent.monkey.patch_all defaults to patching Event.
gevent.subprocess.Popen accepts the same keyword arguments in
Python 2 as it does in Python 3.
gevent.monkey.patch_all and the various individual patch
functions, emit events as patching is being done. This can be used
to extend the patching process for new modules. patch_all also
passes all unknown keyword arguments to these events. See
pull request #1169.
The module gevent.events contains the events that parts of
gevent can emit. It will use zope.event if that is installed.
One of the C libraries that are bundled with gevent have been updated. c-ares has been updated from 1.13.0 to 1.14.0 (c-ares release notes).
This release is intended to be compatible with 1.2.x with no changes to client source code, so long as only non-deprecated and supported interfaces were used (as always, internal, non-documented implementation details may have changed). Here are some specific compatibility notes.
The resolvers have been refactored. As a result,
gevent.ares, gevent.resolver_ares and
gevent.resolver_thread have been deprecated. Choosing a resolver
by alias (e.g., ‘thread’) in the GEVENT_RESOLVER environment
variable continues to work as before.
The internal module gevent._threading was significantly
refactored. As the name indicates this is an internal module not
intended as part of the public API, but such uses have been observed.
The module gevent.wsgi was removed. Use gevent.pywsgi
instead. gevent.wsgi was nothing but an alias for
gevent.pywsgi since gevent 1.0a1 (2011).
Next page: What’s new in gevent 1.2