Release 1.0 (Nov 26, 2013)

  • pywsgi: Pass copy of error list instead of direct reference. Thanks to Jonathan Kamens, Matt Iversen.
  • Ignore the autogenerated doc/gevent.*.rst files. Patch by Matthias Urlichs.
  • Fix on Windows. Patch by Jeryn Mathew.
  • Remove (use gevent.wait).

Release 1.0rc3 (Sep 14, 2013)

  • Fix #251: crash in gevent.core when accessing destroyed loop.
  • Fix #235: Replace self._threadpool.close() with self._threadpool.kill() in Patch by Jan-Philip Gehrcke.
  • Remove unused timeout from (#254). Patch by Saúl Ibarra Corretgé.
  • Rename’s argument to ‘callback’ (closes #244).
  • Fix parallel build (#193). Patch by Yichao Yu.
  • Fix #263: potential UnboundLocalError: ‘length’ in gevent.pywsgi.
  • Simplify (#239). Patch by Alex Gaynor.
  • pywsgi: allow Content-Length in GET requests (#264). Patch by 陈小玉.
  • documentation fixes (#281) [philipaconrad].
  • Fix old documentation about default blocking behavior of kill, killall (#306). Patch by Daniel Farina.
  • Fix #6: patch sys after thread. Patch by Anton Patrushev.
  • subprocess: fix check_output on Py2.6 and older (#265). Thanks to Marc Sibson for test.
  • Fix #302: “python -m gevent.monkey” now sets __file__ properly.
  • pywsgi: fix logging when bound on unix socket (#295). Thanks to Chris Meyers, Eugene Pankov.
  • pywsgi: readout request data to prevent ECONNRESET
  • Fix #303: ‘requestline’ AttributeError in pywsgi. Thanks to Neil Chintomby.
  • Fix #79: Properly handle HTTP versions. Patch by Luca Wehrstedt.
  • Fix #216: propagate errors raised by

Release 1.0rc2 (Dec 10, 2012)

  • Fixed #210: callbacks were not run for non-default loop (bug introduced in 1.0rc1).
  • patch_all() no longer patches subprocess unless subprocess=True is passed.
  • Fixed AttributeError in hub.Waiter.
  • Fixed #181: make hidden imports visible to freezing tools like py2exe. Patch by Ralf Schmitt.
  • Fixed #202: periodically yield when running callbacks (sleep(0) cannot block the event loop now).
  • Fixed #204: os.tp_read/tp_write did not propogate errors to the caller.
  • Fixed #217: do not set SO_REUSEADDR on Windows.
  • Fixed bug in –module argument for gevent.monkey. Patch by Örjan Persson.
  • Remove warning from about mixing fork() and threads.
  • Cleaned up from code that was needed to support older greenlets. Patch by Saúl Ibarra Corretgé.
  • Allow for explicit default loop creation via get_hub(default=True). Patch by Jan-Philip Gehrcke.

Release 1.0rc1 (Oct 30, 2012)

  • Fixed hub.switch() not to touch stacktrace when switching. greenlet restores the exception information correctly since version 0.3.2. gevent now requires greenlet >= 0.3.2
  • Added gevent.wait() and gevent.iwait(). This is like gevent.joinall() but supports more objects, including Greenlet, Event, Semaphore, Popen. Without arguments it waits for the event loop to finish (previously did that). will be removed before final release and gevent.joinall() might be deprecated.
  • Reimplemented loop.run_callback with a list and a single prepare watcher; this fixes the order of spawns and improves performance a little.
  • Fixes Semaphore/Lock not to init hub in __init__, so that it’s possible to have module-global locks without initializing the hub. This fixes monkey.patch_all() not to init the hub.
  • New implementation of callbacks that executes them in the order they were added. core.loop.callback is removed.
  • Fixed 2.5 compatibility.
  • Fixed crash on Windows when request ‘prev’ and ‘attr’ attributes of ‘stat’ watcher. The attribute access still fails, but now with an exception.
  • Added known_failures.txt that lists all the tests that fail. It can be used by via expected option. It’s used when running the test suite in travis.
  • Fixed socket, ssl and fileobject to not mask EBADF error - it is now propogated to the caller. Previously EBADF was converted to empty read/write. Thanks to Vitaly Kruglikov
  • Removed gevent.event.waitall()
  • Renamed FileObjectThreadPool -> FileObjectThread
  • Greenlet: Fixed #143: greenlet links are now executed in the order they were added
  • Synchronize access to FileObjectThread with Semaphore
  • EINVAL is not longer handled in fileobject.


  • Fixed #178: disable monkey patch
  • Fixed monkey.patch_thread() to patch threading._DummyThread to avoid leak in threading._active. Original patch by Wil Tan.
  • added Event=False argument to patch_all() and patch_thread
  • added patch_sys() which patches stdin, stdout, stderr with FileObjectThread wrappers. Experimental / buggy.
  • monkey patching everything no longer initializes the hub/event loop.


  • create_connection: do not lookup IPv6 address if IPv6 is unsupported. Patch by Ralf Schmitt.


  • Fixed #86: bytearray is now supported. Original patch by Aaron Westendorf.
  • Fixed #116: Multiline HTTP headers are now handled properly. Patch by Ralf Schmitt.


  • Fixed Windows compatibility. The wait() method now also supports ‘timeout’ argument on Windows.
  • Popen: Added rawlink() method, which makes Popen objects supported by gevent.wait(). Updated examples/
  • Fixed #148: read from errpipe_read in small chunks, to avoid trigger EINVAL issue on Mac OS X. Patch by Vitaly Kruglikov
  • Do os._exit() in “finally” section to avoid executing unrelated code. Patch by Vitaly Kruglikov.


  • improve getaddrinfo: For string ports (e.g. “http”) resolver_ares/getaddrinfo previously only checked either getservbyname(port, “tcp”) or getservbyname(port, “udp”), but never both. It now checks both of them.
  • now accepts strings as arguments
  • upgraded c-ares to cares-1_9_1-12-g805c736
  • it is now possible to configure resolver_ares directly with environ, like GEVENTARES_SERVERS


  • Renamed threadpool_read/write to tp_read/write.
  • Removed posix_read, posix_write.
  • Added nb_read, nb_write, make_nonblocking.


  • The system error is now raised immediatelly in main greenlet in all cases.
  • Dropped support for old greenlet versions (need >= 0.3.2 now)


  • allow ‘callback’ property of watcher to be set to None. “del w.callback” no longer works.
  • added missing ‘noinotify’ flag


  • gevent.thread: allocate_lock is now an alias for LockType/Semaphore. That way it does not fail when being used as class member.
  • Updated to start timeouts with ref=False.
  • pool: remove unused get_values() function
  • now recognizes GEVENTSETUP_EV_VERIFY env var which sets EV_VERIFY macro when compiling
  • Added a few micro benchmarks
  • stdlib tests that we care about are now included in greentest/2.x directories, so we don’t depend on them being installed system-wide
  • updated util/
  • the testrunner was completely rewritten.

Release 1.0b4 (Sep 6, 2012)

  • Added gevent.os module with ‘read’ and ‘write’ functions. Patch by Geert Jansen.
  • Moved gevent.hub.fork to gevent.os module (it is still available as gevent.fork).
  • Fixed issue #148: Made fileobject handle EINVAL, which is randomly raised by on Mac OS X. Thanks to Mark Hingston.
  • Fixed issue #150: gevent.fileobject.SocketAdapter.sendall() could needlessly wait for write event on the descriptor. Original patch by Mark Hingston.
  • Fixed AttributeError in baseserver. In case of error, start() would call kill() which was renamed to close(). Thanks to Vitaly Kruglikov.

Release 1.0b3 (Jul 27, 2012)

  • New gevent.subprocess module
  • New gevent.fileobject module
  • Fixed ThreadPool to discard references of the objects passed to it (function, arguments) asap. Previously they could be stored for unlimited time until the thread gets a new job.
  • Fixed #138: gevent.pool.Pool().imap_unordered hangs with an empty iterator. Thanks to exproxus.
  • Fixed #127: could raise TypeError in certain cases. Thanks to Johan Mjones.
  • Fixed socket.makefile() to keep the timeout setting of the socket instance. Thanks to Colin Marc.
  • Added ‘copy()’ method to queues.
  • The ‘nochild’ event loop config option is removed. The install_sigchld offer more flexible way of enabling child watchers.
  • core: all watchers except for ‘child’ now accept new ‘priority’ keyword argument
  • gevent.Timeout accepts new arguments: ‘ref’ and ‘priority’. The default priority for Timeout is -1.
  • Hub.wait() uses Waiter now instead of raw switching
  • Updated libev to the latest CVS version
  • Made pywsgi to raise an AssertionError if non-zero content-length is passed to start_response(204/304) or if non-empty body is attempted to be written for 304/204 response
  • Removed pywsgi feature to capitalize the passed headers.
  • Fixed util/ to work on python3.2 (#123). Patch by Alexandre Kandalintsev.
  • Added ‘closed’ readonly property to socket.
  • Added ‘ref’ read/write property to socket.
  • now parses CARES_EMBED and LIBEV_EMBED parameters, in addition to EMBED.
  • gevent.reinit() and gevent.fork() only reinit hub if it was created and do not create it themselves
  • Fixed not to add libev and c-ares to include dirs in non-embed mode. Patch by Ralf Schmitt.
  • Renamed util/ to util/
  • now saves more information about the system; the stat printing functionality is moved to a separate util/ script.

Release 1.0b2 (Apr 11, 2012)

Major and backward-incompatible changes:

  • Made the threadpool-based resolver the default. To enable the ares-based resolver, set GEVENT_RESOLVER=ares env var.
  • Added support for child watchers (not available on Windows). - Libev loop now reaps all children by default. - If NOCHILD flag is passed to the loop, child watchers and child reaping are disabled.
  • Renamed gevent.coros to gevent.lock. The gevent.coros is still available but deprecated.
  • Added ‘stat’ watchers to loop.
  • The now recognizes gevent_embed env var. When set to “no”, bundled c-ares and libev are ignored.
  • Added optional ‘ref’ argument to sleep(). When ref=false, the watchers created by sleep() do not hold from exiting.
  • ThreadPool now calls Hub.handle_error for exceptions in worker threads.
  • ThreadPool got new method: apply_e.
  • Added new extension module gevent._util and moved gevent.core.set_exc_info function there.
  • Added new extension module gevent._semaphore. It contains Semaphore class which is imported by gevent.lock as gevent.lock.Semaphore. Providing Semaphore in extension module ensures that trace function set with settrace will not be called during __exit__. Thanks to Ralf Schmitt.
  • It is now possible to kill or pre-spawn threads in ThreadPool by setting its ‘size’ property.


  • Make sure the default loop cannot be destroyed more than once, thus crashing the process.
  • Make Hub.destroy() method not to destroy the default loop, unless destroy_loop is True. Non-default loops are still destroyed by default.
  • loop: Removed properties from loop: fdchangecnt, timercnt, asynccnt.
  • loop: Added properties: sigfd, origflags, origflags_int
  • loop: The EVFLAG_NOENV is now always passed to libev. Thus LIBEV_FLAGS env variable is no longer checked. Use GEVENT_BACKEND.


  • Check that the argument of link() is callable. Raise TypeError when it’s not.
  • Fixed TypeError in baseserver when parsing an address.
  • Pool: made add() and discard() usable by external users. Thanks to Danil Eremeev.
  • When specifying a class to import, it is now possible to use format path/
  • pywsgi: Made sure format_request() does not fail if ‘status’ attribute is not set yet
  • pywsgi: Added REMOTE_PORT variable to the environment.


  • now shows how to use to implement graceful shutdown of a server.
  • Changed execute() to return rowcount.
  • Added fetchall() and fetchiter() methods.

Developer utilities:

  • When building, CYTHON env variable can be used to specify Cython executable to use.
  • util/ now recongizes –fast and –revert options. Previous –rsync option is removed.
  • Added util/ which automates building/testing/making binaries on Windows VM.
  • Fixed typos in exception handling code in
  • Fixed patching unittest.runner on Python2.7. This caused the details of test cases run lost.
  • Made kill the whole process group after test is done.

Release 1.0b1 (Jan 10, 2012)

Backward-incompatible changes:

  • Removed “link to greenlet” feature of Greenlet.
  • If greenlet module older than 0.3.2 is used, then greenlet.GreenletExit.__bases__ is monkey patched to derive from BaseException and not Exception. That way gevent.GreenletExit is always derived from BaseException, regardless of installed greenlet version.
  • Some code supporting Python 2.4 has been removed.

Release highlights:

  • Added thread pool: gevent.threadpool.ThreadPool.
  • Added thread pool-based resolver. Enable with GEVENT_RESOLVER=thread.
  • Added UDP server: gevent.server.DatagramServer
  • A “configure” is now run on libev. This fixes a problem of ‘kqueue’ not being available on Mac OS X.
  • Gevent recognizes some environment variables now: - GEVENT_BACKEND allows passing argument to loop, e.g. “GEVENT_BACKEND=select” for force select backend - GEVENT_RESOLVER allows choosing resolver class. - GEVENT_THREADPOOL allows choosing thread pool class.
  • Added new examples: portforwarder,,,
  • Fixed non-embedding build. To build against system libev, remove or rename ‘libev’ directory. To build against system c-ares, remove or rename ‘c-ares’. Thanks to Örjan Persson.

misc: - gevent.joinall() method now accepts optional ‘count’ keyword. - gevent.fork() only calls reinit() in the child process now. - now returns False when exiting because of timeout or event (previous None). - Hub got a new method: destroy(). - Hub got a new property: threadpool.

ares.pyx: - Fixed issue #104: made ares_host_result pickable. Thanks to Shaun Cutts.

pywsgi: - Removed unused deprecated ‘wfile’ property from WSGIHandler - Fixed issue #92: raise IOError on truncated POST requests. - Fixed issue #93: do not sent multiple “100 continue” responses

core: - Fixed issue #97: the timer watcher now calls ev_now_update() in start() and again() unless ‘update’ keyword is passed and set to False. - add set_syserr_cb() function; it’s used by gevent internally. - gevent now installs syserr callback using libev’s set_syserr_cb. This callback is called when libev encounters an error it cannot recover from. The default action is to print a message and abort. With the callback installed, a SystemError() is now raised in the main greenlet. - renamed ‘backend_fd’ property to ‘fileno()’ method. (not available if you build gevent against system libev) - added ‘asynccnt’ property (not available if you build gevent against system libev) - made loop.__repr__ output a bit more compact - the watchers check the arguments for validness now (previously invalid argument would crash libev). - The ‘async’ watcher now has send() method; - fixed time() function - libev has been upgraded to latest CVS version. - libev has been patched to use send()/recv() for evpipe on windows when libev_vfd.h is in effect

resolver_ares: - Slightly improved compatibility with stdlib’s socket in some error cases.

socket: - Fixed close() method not to reference any globals - Fixed issue #115: _dummy gets unexpected Timeout arg - Removed _fileobject used for python 2.4 compatibility in - Fixed issue #94: fallback to buffer if memoryview fails in _get_memory on python 2.7

monkey: - Removed patch_httplib() - Fixed issue #112: threading._sleep is not patched. Thanks to David LaBissoniere. - Added get_unpatched() function. However, it is slightly broken at the moment.

backdoor: - make ‘locals()’ not spew out __builtin__.__dict__ in backdoor - add optional banner argument to BackdoorServer

servers: - add server.DatagramServer; - StreamServer: ‘ssl_enabled’ is now a read-only property - servers no longer have ‘kill’ method; it has been renamed to ‘close’. - listeners can now be configured as strings, e.g. ‘:80’ or 80 - modify baseserver.BaseServer in such a way that makes it a good base class for both StreamServer and DatagramServer - BaseServer no longer accepts ‘backlog’ parameter. It is now done by StreamServer. - BaseServer implements start_accepting() and stop_accepting() methods - BaseServer now implements “temporarily stop accepting” strategy - BaseServer now has _do_read method which does everything except for actually calling accept()/recvfrom() - pre_start() method is renamed to init_socket() - renamed _stopped_event to _stop_event - ‘started’ is now a read-only property (which actually reports state of _stop_event) - post_stop() method is removed - close() now sets _stop_event(), thus setting ‘started’ to False, thus causing serve_forever() to exit - _tcp_listener() function is moved from to - added ‘fatal_errors’ class attribute which is a tuple of all errnos that should kill the server

coros: - Semaphore: add _start_notify() method - Semaphore: avoid copying list of links; rawlink() no longer schedules notification

Release 1.0a3 (Sep 15, 2011)

Added ‘ref’ property to all watchers. Settings it to False make watcher call ev_unref/ev_ref appropriately so that this watcher does not prevent from exiting. Made resolver_ares.Resolver use ‘ref’ property for internal watcher.

In all servers, method “kill” was renamed to “close”. The old name is available as deprecated alias.

Added a few properties to the loop: backend_fd, fdchangecnt, timercnt.

Upgraded c-ares to 1.7.5+patch.

Fixed getaddrinfo to return results in the order (::1, IPv4, IPv6).

Fixed getaddrinfo() to handle integer of string type. Thanks to kconor.

Fixed gethostbyname() to handle ‘’ (empty string).

Fixed getaddrinfo() to convert UnicodeEncodeError into error(‘Int or String expected’).

Fixed getaddrinfo() to uses the lowest 16 bits of passed port integer similar to built-in _socket.

Fixed getnameinfo() to call getaddrinfo() to process arguments similar to built-in _socket.

Fixed gethostbyaddr() to use getaddrinfo() to process arguments.

version_info is now a 5-tuple.

Added handle_system_error() method to Hub (used internally).

Fixed Hub’s run() method to never exit. This prevent inappropriate switches into parent greenlet.

Fixed Hub.join() to return True if Hub was already dead.

Added ‘event’ argument to Hub.join().

Added run() function to gevent top level package.

Fixed Greenlet.start() to exit silently if greenlet was already started rather than raising AssertionError.

Fixed Greenlet.start() not to schedule another switch if greenlet is already dead.

Fixed gevent.signal() to spawn Greenlet instead of raw greenlet. Also it’ll switch into the new greenlet immediately instead of scheduling additional callback.

Do monkey patch create_connection() as gevent’s version works better with gevent.socket.socket than the standard create_connection.

pywsgi: make sure we don’t try to read more requests if socket operation failed with EPIPE

pywsgi: if we failed to send the reply, change ‘status’ to socket error so that the logs mention the error.

Release 1.0a2 (Aug 2, 2011)

Fixed a bug in gevent.queue.Channel class. (Thanks to Alexey Borzenkov)

Release 1.0a1 (Aug 2, 2011)

Backward-incompatible changes:

  • Dropped support for Python 2.4.
  • Queue(0) is now equivalent to an unbound queue and raises DeprecationError. Use gevent.queue.Channel if you need a channel.
  • Deprecated ability to pass a greenlet instance to, Greenlet.link_value() and Greenlet.link_exception().
  • All of gevent.core has been rewritten and the interface is not compatible.
  • SystemExit and SystemError now kill the whole process instead of printing a traceback.
  • Removed deprecated util.lazy_property property.
  • Removed gevent.dns module.
  • Removed deprecated gevent.sslold module
  • Removed deprecated gevent.rawgreenlet module
  • Removed deprecated name GreenletSet which used to be alias for Group.

Release highlights:

  • The gevent.core module now wraps libev’s API and is not compatible with gevent 0.x.
  • Added a concept of pluggable event loops. By default gevent.core.loop is used, which is a wrapper around libev.
  • Added a concept of pluggable name resolvers. By default a resolver based on c-ares library is used.
  • Added support for multiple OS threads, each new thread will get its own Hub instance with its own event loop.
  • The release now includes and embeds the dependencies: libev and c-ares.
  • The standard signal works now as expected.
  • The unhandled errors are now handled uniformely by Hub.handle_error function.
  • Added Channel class to gevent.queue module. It is equivalent to Queue(0) in gevent 0.x, which is deprecated now.
  • Added method peek() to Queue class.
  • Added idle() function which blocks until the event loop is idle.
  • Added a way to gracefully shutdown the application by waiting for all outstanding greenlets/servers/watchers: Hub.join().
  • Added new gevent.ares C extension which wraps c-ares and provides asynchronous DNS resolver.
  • Added new gevent.resolver_ares module provides synchronous API on top of gevent.ares.

The gevent.socket module:

  • DNS functions now use c-ares library rather than libevent-dns. This fixes a number of problems with name resolving: - Issue #2: DNS resolver no longer breaks after fork(). You still need to call gevent.fork() (os.fork is monkey

    patched with it if monkey.patch_all() was called).

    • DNS resolver no longer ignores /etc/resolv.conf and /etc/hosts.
  • The following functions were added to socket module - gethostbyname_ex - getnameinfo - gethostbyaddr - getfqdn

  • Removed undocumented bind_and_listen and tcp_listener

The Hub object:

  • Added join() method which waits until the event loop exits or optional timeout expires.
  • Added wait() method which waits until a watcher has got an event.
  • Added handle_error() method which is called by all of gevent in case of unhandled exception.
  • Added print_exception() method which is called by handle_error to print the exception traceback.

The Greenlet objects:

  • Added __nonzero__ implementation that returns True after greenlet was started until it’s dead. Previously greenlet was False after start() until it was first switched to.

The mod:gevent.pool module:

  • It is now possible to add raw greenlets to the pool.
  • The map() and imap() methods now start yielding the results as soon as possible.
  • The imap_unordered() no longer swallows an exception raised while iterating its argument.


  • gevent.sleep(<negative value>) no longer raises an exception, instead it does sleep(0).
  • Added method clear to internal Waiter class.
  • Removed wait method from internal Waiter class.
  • The WSGIServer now sets max_accept to 1 if wsgi.multiprocessing is set to True.
  • Added monkey.patch_module() function that monkey patches module using __implements__ list provided by gevent module. All of gevent modules that replace stdlib module now have __implements__ attribute.

Release 0.13.8 (September 6, 2012)

  • Fixed issue #80: gevent.httplib failed with RequestFailed errors because timeout was reset to 1s. Patch by Tomasz Prus.
  • core: fix compilation with the latest Cython: remove emit_ifdef/emit_else/emit_endif.
  • Fixed issue #132: gevent.socket.gethostbyname(<unicode>) now does ascii encoding and uses gevent’s resolver rather than calling built-in resolver. Patch by Alexey Borzenkov.

Release 0.13.7 (April 12, 2012)

  • Fixed #94: fallback to buffer if memoryview fails in _get_memory on python 2.7.
  • Fixed #103: Queue(None).full() returns False now (previously it returned True).
  • Fixed #112: threading._sleep is not patched. Thanks to David LaBissoniere.
  • Fixed #115: _dummy gets unexpected Timeout arg.

Release 0.13.6 (May 2, 2011)

  • Added __copy__ method to gevent.local.local class that implements copy semantics compatible with built-in threading.local. Patch by Galfy Pundee.
  • Fixed StreamServer class to catch EWOULDBLOCK rather than EAGAIN. This fixes lots of spurious tracebacks on Windows where these two constants are not the same. Patch by Alexey Borzenkov.
  • Fixed issue #65: fork() now calls event_reinit only in the child process; otherwise the process could hang when using libevent2. Patch by Alexander Boudkar.

Release 0.13.5 (Apr 21, 2011)

  • Fixed build problem on Python 2.5

Release 0.13.4 (Apr 11, 2011)

  • Fixed TypeError that occurred when environ["wsgi.input"].read function was called with an integer argument.
  • Fixed issue #63: monkey.patch_thread() now patches threading too, even if it’s already imported. Patch by Shaun Lindsay.
  • Fixed issue #64: joinall() and killall() functions used to hang if their argument contained duplicate greenlets.
  • Fixed issue #69: pywsgi.WSGIServer reported “Connection reset by peer” if the client did not close the connection gracefully after the last request. Such errors are now ignored.
  • Fixed issue #67: Made wsgi.WSGIServer add REQUEST_URI to environ. Patch by Andreas Blixt.
  • Fixed issue #71: monkey patching httplib with gevent.httplib used to break HTTPSConnection. Patch by Nick Barkas.
  • Fixed issue #74: create_connection now raises proper exception when getaddrinfo fails.
  • Fixed BaseServer.__repr__() method, BaseServer.server_host and BaseServer.server_port attributes to handle the case of AF_UNIX addresses properly. Previously they assumed address is always a tuple.
  • Fixed pywsgi.WSGIServer to handle AF_UNIX listeners. The server now sets environ["SERVER_NAME"] and environ["SERVER_PORT"] to empty string in such case.
  • Make StreamServer (and thus pywsgi.WSGIServer) accept up to 100 connections per one readiness notification. This behaviour is controlled by StreamServer.max_accept class attribute.
  • If bind fails, the servers now include the address that caused bind to fail in the error message.

Release 0.13.3 (Feb 7, 2011)

  • Fixed typo in gevent.httplib that rendered it unusable.
  • Removed unnecessary delay in getaddrinfo by calling resolve_ipv4 and resolve_ipv6 concurrently rather than sequentially in AF_UNSPEC case.

Release 0.13.2 (Jan 28, 2011)

  • Added gevent.httplibexperimental support for libevent-http client (issue #9). Thanks to Tommie Gannert, Örjan Persson.
  • Fixed crash on Mac OS X (issue #31). Patch by Alexey Borzenkov.
  • Fixed compatiblity of gevent.wsgi with libevent2 (issue #62).
  • Fixed compilation issues with libevent2. Patch by Ralf Schmitt.
  • Fixed pywsgi not to use chunked transfer encoding in case of 304 and 204 responses as it creates a non-empty message body which is against RFC and causes some browsers to fail. Patch by Nicholas Piël.
  • Fixed socket.getaddrinfo() to handle AF_UNSPEC properly and resolve service names (issue #56). Thanks to Elizabeth Jennifer Myers.
  • Fixed socket.getaddrinfo() to handle international domain names.
  • Fixed leaking of traceback object when switching out of greenlet with sys.exc_info set. Leaking is prevented by not preserving traceback at all and only keeping the value of the exception. Thanks to Ned Rockson.
  • Fixed ssl.SSLSocket.unwrap() to shutdown SSLSocket properly, without raising SSLError(read operation timeout).
  • Fixed TypeError inside Hub on Python 2.4.
  • Made a number of internal improvements to gevent.pywsgi to make subclassing easier.
  • Changed WSGIServer to explicitly close the socket after the last request. Patch by Ralf Schmitt.
  • Fixed pywsgi.WSGIHandler not to add CONTENT_TYPE to the environ dict when there’s no Content-Type header in the request. Previously a default text/plain was added in such case.
  • Added proper implementation of imap_unordered to Pool class. Unlike previous “dummy” implementation this one starts yielding the results as soon as they are ready.
  • Implemented iterator protocol in Queue. The main use case is the implementation of Pool.imap_unordered().
  • Fixed BaseServer.started property: it is now set to True after start until stop or kill. Previously it could become False for short period of times, because StreamServer could stop accepting for a while in presence of errors and StreamServer.started was defined as “whether the server is currently accepting”.
  • Fixed wsgi.WSGIServer to reply with 500 error immediatelly if the application raises an error (issue #58). Thanks to Jon Aslund.
  • Added monkey.patch_httplib() function which is disabled by default.
  • Added httplib parameter to monkey.patch_all() (defaults to False).
  • Added write method to core.buffer.
  • Fixed OverflowError that could happen in core.event.__str__().
  • Made http_request.get_input_headers() return header names in lower case.
  • Fixed StreamServer to accept ciphers as an SSL argument.
  • Added build_exc --cython= option to Patch by Ralf Schmitt.
  • Updated local to raise AttributeError if __dict__ attribute is set or deleted.

Release 0.13.1 (Sep 23, 2010)

Release highlights:

  • Fixed monkey to patch socket.create_connection.
  • Updated gevent.ssl module to fully match the functionality of ssl on Python 2.7.
  • Fixed Group.join() to handle raise_error=True properly, it used to raise TypeError (issue #36). Thanks to by David Hain.
  • Fixed gevent.wsgi and gevent.pywsgi to join multiple Cookie headers (issue #40).
  • Fixed select to recognize long arguments in addition to int.
  • Fixed Semaphore.acquire() to return False when timeout expires instead of raising AssertionError (issue #39). Patch by Erik Näslund.
  • Fixed JoinableQueue.join() to return immediatelly if queue is already empty (issue #45). Patch by Dmitry Chechik.
  • Deprecated gevent.sslold module.

gevent.socket module:

  • Overrode socket.shutdown() method to interrupt read/write operations on socket.
  • Fixed possible NameError in socket.connect_ex() method. Patch by Alexey Borzenkov.
  • Fixed socket leak in create_connection() function.
  • Made gevent.socket import all public items from stdlib socket that do not do I/O.

gevent.ssl module:

  • Imported a number of patches from stdlib by Antoine Pitrou:
    • Calling makefile() method on an SSL object would prevent the underlying socket from being closed until all objects get truely destroyed (Python issue #5238).
    • SSL handshake would ignore the socket timeout and block indefinitely if the other end didn’t respond (Python issue #5103).
    • When calling getpeername() in SSLSocket.__init__, only silence exceptions caused by the “socket not connected” condition.
  • Added support for ciphers argument.
  • Updated SSLSocket.send and SSLSocket.recv methods to match the behavior of stdlib ssl better.
  • Fixed ssl.SSLObject to delete events used by other greenlets when closing the instance (issue #34).


  • Made BaseServer accept long values as pool argument in addition to int.
  • Made http._requests attribute public.
  • Updated webchat example to use file on disk rather than in-memory sqlite database to avoid OperationalError.
  • Fixed example to be runnable under external WSGI server.
  • Fixed bogus failure in
  • Added new test to check PEP8 conformance:
  • Fixed BackdoorServer close the connection on SystemExit and simplified the code.
  • Made Pool raise ValueError when initialized with size=0.
  • Updated --libevent to configure and make libevent if it’s not built already.
  • Updated to use setuptools if present and add dependency on greenlet.
  • Fixed doc/ to work with Sphinx 1. Thanks by Örjan Persson.

Release 0.13.0 (Jul 14, 2010)

Release highlights:

  • Added gevent.server module with StreamServer class for easy implementing of TCP and SSL servers.
  • Added gevent.baseserver module with BaseServer class.
  • Added new implementation of gevent.pywsgi based on gevent.server. Contributed by Ralf Schmitt.
  • Added gevent.local module. Fixed issue #24. Thanks to Ted Suzman.
  • Fixed a number of bugs in gevent.wsgi module.
  • Fixed issue #26: closing a socket now interrupts all pending read/write operations on it.
  • Implemented workaround that prevents greenlets from leaking exc_info.
  • Fixed socket.sendall() to use buffer object to prevent string copies.
  • Made the interfaces of gevent.wsgi and gevent.pywsgi much more similar to each other.
  • Fixed compilation on Windows with libevent-2.
  • Improved Windows compatibility. Fixed issue #30. Thanks to Luigi Pugnetti.
  • Fixed compatibility with Python 2.7.

Backward-incompatible changes:

  • Blocking is now the default behaviour for the Greenlet.kill() method and other kill* methods.
  • Changed the inteface of http.HTTPServer to match the interface of other servers.
  • Changed Pool‘s spawn() method to block until there’s a free slot.
  • Removed deprecated backdoor.backdoor_server() function.
  • Removed deprecated functions in socket module:
    • socket_bind_and_listen()
    • set_reuse_addr()
    • connect_tcp()
    • tcp_server()
  • Removed deprecated socket.fd property.
  • Deprecated use of negative numbers to indicate infinite timeout in core.event.add() and socket.wait_read() and similar. Use None from now on, which is compatible with the previous versions.
  • Derived backdoor.BackdoorServer from StreamServer rather than from Greenlet. This adds lots of new features and removes a few old ones.
  • Removed non-standard balance property from Semaphore.
  • Removed start(), set_cb() and set_gencb() from core.http.
  • Removed set_closecb() from core.http_connection. It is now used internally to detach the requests of the closed connections.
  • Deprecated rawgreenlet module.
  • Deprecated util.lazy_property().
  • Renamed GreenletSet to Group. The old name is currently available as an alias.

gevent.socket module:

  • Fixed issues #26 and #34: closing the socket while reading/writing/connecting is now safe. Thanks to Cyril Bay.
  • Imported getfqdn() from socket module.
  • The module now uses sys.platform to detect Windows rather than platform module.
  • Fixed issue #27: getaddrinfo() used to handle the case when socktype or proto were equal to 0. Thanks to Randall Leeds.

gevent.coros module:

  • Added RLock class.
  • Added DummySemaphore class.
  • Fixed BoundedSemaphore class to behave like threading.BoundedSemaphore behaves.

gevent.event module:

  • Made Event.wait() return internal flag instead of None.
  • Made AsyncResult.wait() return its value instead of None.
  • Added ready() method as an alias for is_set().

gevent.wsgi module:

  • Removed wsgi.buffer_proxy.

gevent.pywsgi module:

  • Rewritten to use server and not to depend on BaseHTTPServer.
  • Changed the interface to match wsgi module. Removed server() function, add Server class, added WSGIServer class.
  • Renamed HttpProtocol to WSGIHandler.
  • Fixed compatibility with webob by allowing an optional argument to readline().

gevent.core module:

  • Fixed reference leaks in event class.
  • Avoid Python name lookups when accessing EV_* constants from Cython code. Patch by Daniele Varrazzo.
  • Added persist argument to read_event, write_event and readwrite_event.
  • Made all of the event loop callbacks clear the exception info before exiting.
  • Added flags_str property to event. It is used by __str__ and __repr__.
  • buffer:
    • Added detach() method.
    • Implemented iterator protocol.
    • Fixed readline() and readlines() methods.
  • http_request:
    • Fixed detach() to detach input and output buffers too.
    • Changed the response to send 500 error upon deallocation, if no response was sent by the user.
    • Made input_buffer and output_buffer store and reuse the buffer object they create.
    • Fixed __str__() and meth:__repr__ to include spaces where needed.
    • http class no longer has set_cb() and set_gencb(). Instead its contructor accepts handle which will be called on each request.

gevent.http and gevent.wsgi modules:

  • Made HTTPServer use "Connection: close" header by default.
  • Class HTTPServer now derives from baseserver.BaseServer. Thus its start() method no longer accepts socket to listen on, it must be passed to the contructor.
  • The spawn argument now accepts a Pool instance. While the pool is full, the server replies with 503 error.
  • The server no longer links to the greenlets it spawns to detect errors. Instead, it relies on http_request which will send 500 reply when deallocated if the user hasn’t send any.


  • Changed gevent.thread to use Greenlet instead of raw greenlets. This means monkey patched thread will become Greenlet too.
  • Added started property to Greenlet.
  • Put common server code in gevent.baseserver module. All servers in gevent package are now derived from BaseServer.
  • Fixed issue #20: sleep() now raises IOError if passed a negative argument.
  • Remove the code related to finding out libevent version from as macro USE_LIBEVENT_? is no longer needed to build gevent.core.
  • Increased default backlog in all servers (from 5 to 256). Thanks to Nicholas Piël.
  • Fixed doc/ to work in Python older than 2.6. Thanks to Örjan Persson.
  • Silented SystemError raised in backdoor when a client typed quit().
  • If importing greenlet failed with ImportError, keep the original error message, because sometimes the error originates in setuptools.
  • Changed to return all the file descriptors signalled, not just the first one.
  • Made thread (and thus monkey patched threads) to spawn Greenlet instances, rather than raw greenlets.


  • Updated to use StreamServer.
  • Added
  • Added

Thanks to Ralf Schmitt for pywsgi, a number of fixes for wsgi, help with baseserver and server modules, improving and various other patches and suggestions.

Thanks to Uriel Katz for pywsgi patches.

Release 0.12.2 (Mar 2, 2010)

  • Fixed http server to put the listening socket into a non-blocking mode. Contributed by Ralf Schmitt.

Release 0.12.1 (Feb 26, 2010)

  • Removed a symlink from the distribution (that causes pip to fail). Thanks to Brad Clements for reporting it.
  • automatically create symlink from build/lib.../gevent/ to gevent/
  • gevent.socket: Improved compatibility with stdlib’s socket:
    • Fixed socket to raise timeout("timed out") rather than simply timeout.
    • Imported _GLOBAL_DEFAULT_TIMEOUT from standard socket module instead of creating a new object.

Release 0.12.0 (Feb 5, 2010)

Release highlights:

  • Added gevent.ssl module.
  • Fixed Windows compatibility (experimental).
  • Improved performance of socket.recv(), socket.send() and similar methods.
  • Added a new module - dns - with synchronous wrappers around libevent’s DNS API.
  • Added core.readwrite_event and socket.wait_readwrite() functions.
  • Fixed several incompatibilities of wsgi module with the WSGI spec.
  • Deprecated pywsgi module.

gevent.wsgi module:

  • Made env["REMOTE_PORT"] into a string.
  • Fixed the server to close the iterator returned by the application.
  • Made wsgi.input object iterable.

gevent.core module:

  • Made DNS functions no longer accept/return IP addresses in dots-and-numbers format. They work with packed IPs now.
  • Made DNS functions no longer accept additional arguments to pass to the callback.
  • Fixed DNS functions to check the return value of the libevent functions and raise IOError if they failed.
  • Added core.dns_err_to_string().
  • Made core.event.cancel not to raise if event_del reports an error. instead, the return code is passed to the caller.
  • Fixed minor issue in string representation of the events.

gevent.socket module:

  • Fixed bug in socket.accept. It could return unwrapped socket instance if socket’s timeout is 0.
  • Fixed socket.sendall implementation never to call underlying socket’s sendall.
  • Fixed gethostbyname() and getaddrinfo() to call the stdlib if the passed hostname has no dots.
  • Fixed getaddrinfo() to filter the results using socktype and proto arguments.
  • Removed getnameinfo() as it didn’t quite match the stdlib interface. Use dns.resolve_reverse() for reverse resolutions.
  • Fixed socket.connect_ex() to use cooperative gethostbyname().
  • Fixed socket.dup() not to call underlying socket’s dup() (which is not available on Windows) but to use Python’s reference counting similar to how the stdlib’s socket implements dup()
  • Added _sock argument to socket‘s constructor. Passing the socket instance as first argument is no longer supported.
  • Fixed socket.connect() to ignore WSAEINVAL on Windows.
  • Fixed socket.connect() to use wait_readwrite() instead of wait_write().
  • Fixed socket.connect() to consult SO_ERROR.
  • Fixed socket.send() and socket.sendall() to support flags argument.
  • Renamed socket_bind_and_listen() to socket.bind_and_listen(). The old name is still available as a deprecated alias.
  • The underlying socket object is now stored as _sock property.
  • Imported the constants and some utility functions from stdlib’s socket into gevent.socket. (Thanks to Matt Goodall for the original patch).
  • Renamed wrap_ssl() to ssl(). (the old name is still available but deprecated)
  • Deprecated connect_tcp() and tcp_server().
  • Added sslerror to socket.__all__.
  • Removed GreenSocket alias for socket class.
  • Moved PyOpenSSL-based implementation of socket.ssl() into gevent.oldssl module. It’s imported into gevent.socket if importing gevent.ssl fails.


  • Fixed Greenlet.spawn_link* and GreenletSet.spawn_link* classmethods not to assume anything about their arguments. (Thanks to Marcus Cavanaugh for pointing that out).
  • Fixed select to clean up properly if event creation fails.
  • Fixed select to raise select.error instead of IOError.
  • Fixed to proceed with compilation even if libevent version cannot be determined. 1.x.x is assumed in this case.
  • Fixed compatibility of .pyx files with Cython 0.12.0.
  • Renamed arguments for to what they are called in the stdlib.
  • Removed internal function getLinkedCompleted() from gevent.greenlet.
  • Remove #warning directives from libevent.h. They are not supported by vc90.
  • Removed some deprecated stuff from coros.
  • Internal class Waiter now stores the value if no one’s waiting for it.
  • Added script that replaces a bunch of small scripts that were used before.
  • Removed is_secure attribute from sockets and ssl objects.
  • Made Greenlet not to print a traceback when a not-yet-started greenlet is killed.
  • Added BackdoorServer class to backdoor. Removed backdoor() function and deprecated backdoor_server() function.
  • Removed __getattr__ from socket class.
  • Fixed monkey.patch_socket() not to fail if socket.ssl() is not present in gevent.socket.
  • Added monkey.patch_ssl().
  • Added aggressive argument to monkey.patch_all().
  • Tests from stdlib no longer included in greentest package. Instead, there are number of stubs that import those tests from test package directly and run them in monkey patched environment.
  • Added examples/ by Marcus Cavanaugh.

Release 0.11.2 (Dec 10, 2009)

  • Fixed wsgi to unquote environ['PATH_INFO'] before passing to application.
  • Added SERVER_SOFTWARE variable to wsgi environ.
  • Fixed bug in JoinableQueue.task_done() that caused ValueError to be raised incorrectly here.
  • Fixed gevent.socket not to fail with ImportError if Python was not built with ssl support.

Release 0.11.1 (Nov 15, 2009)

  • Fixed bug in function. Passing non-empty list of write descriptors used to cause this function to fail.
  • Changed to go ahead with the compilation even if the actual version of libevent cannot be determined (version 1.x.x is assumed in that case).

Contributed by Ludvig Ericson:

  • Fixed wsgi‘s start_response to recognize exc_info argument.
  • Fixed to look for libevent.dylib rather than .so on Darwin platforms.

Release 0.11.0 (Oct 9, 2009)

  • Fixed timeout bug in joinall(), Greenlet.join(), pool.Pool.join(): if timeout has expired it used to raise Timeout; now it returns silently.
  • Fixed signal() to run the signal handler in a new greenlet; it was run in the Hub greenlet before.
  • Fixed Timeout.start_new(): if passed a Timeout instance, it now calls its start method before returning it.
  • Fixed gevent.monkey to patch threading.local properly.
  • Fixed Queue.empty() and Queue.full() to be compatible with the standard Queue. It tried to take into account the greenlets currently blocking on get/put which was not useful and hard to reason about. Now it simply compares qsize to maxsize, which what the standard Queue does too.
  • Fixed Event to behave exactly like the standard threading.Event:
    • Event.set() does not accept a parameter anymore; it’s now either set or not.
    • Event.get method is gone.
    • Event.set(); Event.clear() used to be a no-op; now it properly wakes up all the waiters.
    • AsyncResult behaves exactly like before, but it does not inherit from Event anymore and does miss clear() method.
  • Renamed internal helpers socket.wait_reader()/socket.wait_writer() to socket.wait_read()/socket.wait_write().
  • Renamed gevent.socket.GreenSocket to gevent.socket.socket. GreenSocket is still available as an alias but will be removed in the future.
  • gevent.core now includes wrappers for evbuffer, evdns, evhttp.
  • Renamed the old gevent.wsgi to gevent.pywsgi.
  • Added a new HTTP server gevent.http module based on libevent-http wrappers.
  • Added a new WSGI server gevent.wsgi module based on gevent.http.
  • Added evdns wrappers to gevent.core and DNS functions to gevent.socket module. Contributed by Jason Toffaletti..
  • Added a few a few options to to select a libevent library to compile against. Check them out with -h.
  • Added __all__ to many modules that missed it.
  • Converted the docstrings and the changelog to sphinx/rst markup.
  • Added sphinx/rst documentation. It is available online at

Release 0.10.0 (Aug 26, 2009)

  • Changed Timeout API in a backward-incompatible way: Timeout.__init__() does not start the timer immediately anymore; Timeout.start() must be called explicitly. A shortcut - Timeout.start_new() - is provided that creates and starts a Timeout.

  • Added gevent.Greenlet class which is a subclass of greenlet that adds a few useful methods join/get/kill/link.

  • spawn() now returns Greenlet instance. The old spawn, which returns py.magic.greenlet instance, can be still accessed as spawn_raw().


    The implementation of Greenlet is an improvement on proc module, with these bugs fixed:

    • Proc was not a subclass of greenlet which makes getcurrent() useless and using Procs as keys in dict impossible.
    • Proc executes links sequentially, so one could block the rest from being executed. Greenlet executes each link in a new greenlet by default, unless it is set up with Greenlet.rawlink method.
    • Proc cannot be easily subclassed. To subclass Greenlet, override its _run and __init__ methods.
  • Added pool.Pool class with the methods compatible to the standard multiprocessing.pool: apply, map and others. It also has spawn method which is always async and returns a Greenlet instance.

  • Added gevent.event module with 2 classes: Event and AsyncResult. Event is a drop-in replacement for threading.Event, supporting set/wait/get methods. AsyncResult is an extension of Event that supports exception passing via set_exception method.

  • Added queue.JoinableQueue class with task_done and join methods.

  • Renamed and core.write classes to core.read_event and core.write_event.

  • gevent.pywsgi: pulled Mike Barton’s eventlet patches that fix double content-length issue.

  • Fixed to search more places for system libevent installation. This fixes 64bit CentOS 5.3 installation issues, hopefully covers other platforms as well.

The following items were added to the gevent top level package:

The following items were marked as deprecated:

  • gevent.proc module (wrap_errors helper was moved to util module)
  • gevent.coros.event
  • gevent.coros.Queue and gevent.coros.Channel

Internally, gevent.greenlet was split into a number of modules:

  • gevent.hub provides Hub class and basic utilities, like sleep(); Hub is now a subclass of greenlet.
  • gevent.timeout provides Timeout and with_timeout();
  • gevent.greenlet provides Greenlet class and helpers like joinall() and killall().
  • gevent.rawgreenlet contains the old “polling” versions of joinall and killall (they do not need link functionality and work with any greenlet by polling their status and sleeping in a loop)

Thanks to Jason Toffaletti for reporting the installation issue and providing a test case for WSGI double content-length header bug.

Release 0.9.3 (Aug 3, 2009)

  • Fixed all known bugs in the gevent.queue module and made it 2.4-compatible. LifoQueue and PriorityQueue are implemented as well. gevent.queue will deprecate both coros.Queue and coros.Channel.
  • Fixed Timeout to raise itself by default. TimeoutError is gone. Silent timeout is now created by passing False instead of None.
  • Fixed bug in where it could silent the wrong timeout.
  • spawn() and spawn_later() now avoid creating a closure and this decreases spawning time by 50%.
  • kill‘s and killall‘s wait argument was renamed to block. The polling is now implemented by greenlet.join and greenlet.joinall functions and it become more responsive, with gradual increase of sleep time.
  • Renamed proc.RunningProcSet to proc.ProcSet.
  • Added shutdown() function, which blocks until libevent has finished dispatching the events.
  • The return value of event_add and event_del in core.pyx are now checked properly and IOError is raised if they have failed.
  • Fixed, accidentally broken in the previous release.

Release 0.9.2 (Jul 20, 2009)

  • Simplified gevent.socket‘s implementation and fixed SSL bug reported on eventletdev by Cesar Alaniz as well as failures in
  • Removed GreenSocket.makeGreenFile; Use socket.socket.makefile() that returns _fileobject and is available on both GreenSocket and GreenSSL. The gevent.socket is still a work in progress.
  • Added new core.active_event class that takes advantage of libevent’s event_active function. core.active_event(func) schedules func to be run in this event loop iteration as opposed to core.timer(0, ...) which schedules an event to be run in the next iteration. active_event is now used throughout the library wherever core.timer(0, ....) was previously used. This results in spawn() being at least 20% faster compared to release 0.9.1 and twice as fast compared to eventlet. (The results are obtained with script in greentest/ directory)
  • Added boolean parameter wait to kill() and killall() functions. If set to True, it makes the function block until the greenlet(s) is actually dead. By default, kill() and killall() are asynchronous, i.e. they don’t unschedule the current greenlet.
  • Added a few new properties to gevent.core.event: fd, events, events_str and flags. It also has __enter__ and __exit__ now, so it can be used as a context manager. event‘s callback signature has changed from (event, fd, evtype) to (event, evtype).
  • Fixed Hub‘s mainloop to never return successfully as this will screw up main greenlet’s switch() call. Instead of returning it raises DispatchExit.
  • Added reinit() function - wrapper for libevent’s event_reinit. This function is a must have at least for daemons, as it fixes epoll and some others eventloops to work after fork.
  • Trying to use gevent in another thread will now raise an exception immediately, since it’s not implemented.
  • Added a few more convenience methods spawn_link[exception/value] to proc.RunningProcSet.
  • Fixed not to depend on setuptools.
  • Removed gevent.timeout. Use gevent.Timeout.

Release 0.9.1 (Jul 9, 2009)

  • Fixed compilation with libevent-1.3. Thanks to Litao Wei for reporting the problem.
  • Fixed Hub to recover silently after event_dispatch() failures (I’ve seen this happen after fork even though event_reinit() is called as necessary). The end result is that fork() now works more reliably, as detected by - it used to fail occasionally, now it does not.
  • Reorganized the package, most of the stuff from gevent/ was moved to gevent/ gevent/ imports some of it back but not everything.
  • Renamed gevent.timeout to gevent.Timeout. The old name is available as an alias.
  • Fixed a few bugs in queue.Queue. Added from standard tests to check how good is queue.Queue a replacement for a standard Queue (not good at all, timeouts in queue.Queue.put() don’t work yet)
  • monkey now patches ssl module when on 2.6 (very limited support).
  • Improved compatibility with Python 2.6 and Python 2.4.
  • Greenlet installed from PyPI (without py.magic prefix) is properly recognized now.
  • core.pyx was accidentally left out of the source package, it’s included now.
  • GreenSocket now wraps a socket object from _socket module rather than from socket.

Release 0.9.0 (Jul 8, 2009)

Started as eventlet 0.8.11 fork, with the intention to support only libevent as a backend. Compared to eventlet, this version has a much simpler API and implementation and a few severe bugs fixed, namely

  • Full duplex in sockets, i.e. read() and write() on the same fd do not cancel one another.
  • The GreenSocket.close method does not hang as it could with eventlet.

There’s a test in my repo of eventlet that reproduces both of them:

Besides having less bugs and less code to care about the goals of the fork are:

  • Piggy-back on libevent as much as possible (use its http and dns code).
  • Use the interfaces and conventions from the standard Python library where possible.