.. currentmodule:: gevent

• Update autoconf files for Apple Silicon Macs. Note that while there are reports of compiling gevent on Apple Silicon Macs now, this is not a tested configuration. There may be some remaining issues with CFFI on some systems as well. See :issue:`1721`.

• Build and upload CPython 3.10 binary manylinux wheels.

  Unfortunately, this required us to stop building and uploading CPython 2.7 binary manylinux wheels. Binary wheels for 2.7 continue to be available for Windows and macOS. See :issue:`1822`.

• Test and distribute musllinux_1_1 wheels. See :issue:`1837`.

• Update the tested versions of PyPy2 and PyPy3. For PyPy2, there should be no user visible changes, but for PyPy3, support has moved from Python 3.6 to Python 3.7. See :issue:`1843`.

• Try to avoid linking to two different Python runtime DLLs on Windows. See :issue:`1814`.
• Stop compiling manylinux wheels with -ffast-math. This was implicit in -Ofast, but could alter the global state of the process. Analysis and fix thanks to Ilya Konstantinov. See :issue:`1820`.
• Fix hanging the interpreter on shutdown if gevent monkey patching occurred on a non-main thread in Python 3.9.8 and above. (Note that this is not a recommended practice.) See :issue:`1839`.

• Update the embedded c-ares from 1.16.1 to 1.17.1. See :issue:`1758`.

• Add support for Python 3.10rc1 and newer.

  As part of this, the minimum required greenlet version was increased to 1.1.0 (on CPython), and the minimum version of Cython needed to build gevent from a source checkout is 3.0a9.

  Note that the dnspython resolver is not available on Python 3.10. See :issue:`1790`.

• Update from Cython 3.0a6 to 3.0a9. See :issue:`1801`.

• See :issue:`1789`.

• Update the embedded libev from 4.31 to 4.33. See :issue:`1754`.
• Update the embedded libuv from 1.38.0 to 1.40.0. See :issue:`1755`.

• See :issue:`1753`.

Fix a TypeError on startup on Python 2 with zope.schema installed. Reported by Josh Zuech.

• Make gevent FileObjects more closely match the semantics of native file objects for the name attribute:

  • Objects opened from a file descriptor integer have that integer as their name. (Note that this is the Python 3 semantics; Python 2 native file objects returned from os.fdopen() have the string "<fdopen>" as their name , but here gevent always follows Python 3.)
  • The name remains accessible after the file object is closed.

  Thanks to Dan Milon. See :issue:`1745`.

Make gevent.event.AsyncResult print a warning when it detects improper cross-thread usage instead of hanging.

AsyncResult has never been safe to use from multiple threads. It, like most gevent objects, is intended to work with greenlets from a single thread. Using AsyncResult from multiple threads has undefined semantics. The safest way to communicate between threads is using an event loop async watcher.

Those undefined semantics changed in recent gevent versions, making it more likely that an abused AsyncResult would misbehave in ways that could cause the program to hang.

Now, when AsyncResult detects a situation that would hang, it prints a warning to stderr. Note that this is best-effort, and hangs are still possible, especially under PyPy 7.3.3.

At the same time, AsyncResult is tuned to behave more like it did in older versions, meaning that the hang is once again much less likely. If you were getting lucky and using AsyncResult successfully across threads, this may restore your luck. In addition, cross-thread wakeups are faster. Note that the gevent hub now uses an extra file descriptor to implement this.

Similar changes apply to gevent.event.Event (see :issue:`1735`).

See :issue:`1739`.

• Make :class:`gevent.Greenlet` objects function as context managers. When the with suite finishes, execution doesn't continue until the greenlet is finished. This can be a simpler alternative to a :class:`gevent.pool.Group` when the lifetime of greenlets can be lexically scoped.

  Suggested by André Caron. See :issue:`1324`.

• Make gevent's Semaphore objects properly handle native thread identifiers larger than can be stored in a C long on Python 3, instead of raising an OverflowError.

  Reported by TheYOSH. See :issue:`1733`.

• Make worker threads created by :class:`gevent.threadpool.ThreadPool` install the :func:`threading.setprofile` and :func:`threading.settrace` hooks while tasks are running. This provides visibility to profiling and tracing tools like yappi.

  Reported by Suhail Muhammed. See :issue:`1678`.

• Drop support for Python 3.5.

• Incorrectly passing an exception instance instead of an exception type to gevent.Greenlet.kill or gevent.killall no longer prints an exception to stderr. See :issue:`1663`.

• Make destroying a hub try harder to more forcibly stop loop processing when there are outstanding callbacks or IO operations scheduled.

  Thanks to Josh Snyder (:issue:`1686`) and Jan-Philip Gehrcke (:issue:`1669`). See :issue:`1686`.

• Improve the ability to use monkey-patched locks, and gevent.lock.BoundedSemaphore, across threads, especially when the various threads might not have a gevent hub or any other active greenlets. In particular, this handles some cases that previously raised LoopExit or would hang. Note that this may not be reliable on PyPy on Windows; such an environment is not currently recommended.

  The semaphore tries to avoid creating a hub if it seems unnecessary, automatically creating one in the single-threaded case when it would block, but not in the multi-threaded case. While the differences should be correctly detected, it's possible there are corner cases where they might not be.

  If your application appears to hang acquiring semaphores, but adding a call to gevent.get_hub() in the thread attempting to acquire the semaphore before doing so fixes it, please file an issue. See :issue:`1698`.

• Make error reporting when a greenlet suffers a RecursionError more reliable.

  Reported by Dan Milon. See :issue:`1704`.

• gevent.pywsgi: Avoid printing an extra traceback ("TypeError: not enough arguments for format string") to standard error on certain invalid client requests.

  Reported by Steven Grimm. See :issue:`1708`.

• Add support for PyPy2 7.3.3. See :issue:`1709`.

• Python 2: Make gevent.subprocess.Popen.stdin objects have a write method that guarantees to write the entire argument in binary, unbuffered mode. This may require multiple trips around the event loop, but more closely matches the behaviour of the Python 2 standard library (and gevent prior to 1.5). The number of bytes written is still returned (instead of None). See :issue:`1711`.

• Make gevent.pywsgi stop trying to enforce the rules for reading chunked input or Content-Length terminated input when the connection is being upgraded, for example to a websocket connection. Likewise, if the protocol was switched by returning a 101 status, stop trying to automatically chunk the responses.

  Reported by Kavindu Santhusa. See :issue:`1712`.

• Remove the __dict__ attribute from gevent.socket.socket objects. The standard library socket do not have a __dict__.

  Noticed by Carson Ip.

  As part of this refactoring, share more common socket code between Python 2 and Python 3. See :issue:`1724`.

• The embedded libev is now asked to detect the availability of clock_gettime and use the realtime and/or monotonic clocks, if they are available.

  On Linux, this can reduce the number of system calls libev makes. Originally provided by Josh Snyder. See :issue:`1648`.

• On CPython, depend on greenlet >= 0.4.17. This version is binary incompatible with earlier releases on CPython 3.7 and later.

  On Python 3.7 and above, the module gevent.contextvars is no longer monkey-patched into the standard library. contextvars are now both greenlet and asyncio task local. See :issue:`1656`. See :issue:`1674`.

• The DummyThread objects created automatically by certain operations when the standard library threading module is monkey-patched now match the naming convention the standard library uses ("Dummy-12345"). Previously (since gevent 1.2a2) they used "DummyThread-12345". See :issue:`1659`.

• Fix compatibility with dnspython 2.

  Caution!

  This currently means that it can be imported. But it cannot yet be used. gevent has a pinned dependency on dnspython < 2 for now.

  See :issue:`1661`.

• It is now possible to build and use the embedded libuv on a Cygwin platform.

  Note that Cygwin is not an officially supported platform of upstream libuv and is not tested by gevent, so the actual working status is unknown, and this may bitrot in future releases.

  Thanks to berkakinci for the patch. See :issue:`1645`.

• Relax the version constraint for psutil on PyPy.

  Previously it was pinned to 5.6.3 for PyPy2, except for on Windows, where it was excluded. It is now treated the same as CPython again. See :issue:`1643`.

• gevent's CI is now tested on Ubuntu 18.04 (Bionic), an upgrade from 16.04 (Xenial). See :issue:`1623`.

• On Python 2, the dnspython resolver can be used without having selectors2 installed. Previously, an ImportError would be raised. See :issue:`1641`.

• Python 3 gevent.ssl.SSLSocket objects no longer attempt to catch ConnectionResetError and treat it the same as an SSLError with SSL_ERROR_EOF (typically by suppressing it).

  This was a difference from the way the standard library behaved (which is to raise the exception). It was added to gevent during early testing of OpenSSL 1.1 and TLS 1.3. See :issue:`1637`.

• Add gevent.selectors containing GeventSelector. This selector implementation uses gevent details to attempt to reduce overhead when polling many file descriptors, only some of which become ready at any given time.

  This is monkey-patched as selectors.DefaultSelector by default.

  This is available on Python 2 if the selectors2 backport is installed. (This backport is installed automatically using the recommended extra.) When monkey-patching, selectors is made available as an alias to this module. See :issue:`1532`.

• Depend on greenlet >= 0.4.16. This is required for CPython 3.9 and 3.10a0. See :issue:`1627`.

• Add support for Python 3.9.

  No binary wheels are available yet, however. See :issue:`1628`.

• gevent.socket.create_connection and gevent.socket.socket.connect no longer ignore IPv6 scope IDs.

  Any IP address (IPv4 or IPv6) is no longer subject to an extra call to getaddrinfo. Depending on the resolver in use, this is likely to change the number and order of greenlet switches. (On Windows, in particular test cases when there are no other greenlets running, it has been observed to lead to LoopExit in scenarios that didn't produce that before.) See :issue:`1634`.

• Forking a process that had use the threadpool to run tasks that created their own hub would fail to clean up the threadpool by raising greenlet.error. See :issue:`1631`.

• Waiters on Event and Semaphore objects that call wait() or acquire(), respectively, that find the Event already set, or the Semaphore available, no longer "cut in line" and run before any previously scheduled greenlets. They now run in the order in which they arrived, just as waiters that had to block in those methods do. See :issue:`1520`.

• Update tested PyPy version from 7.3.0 to 7.3.1 on Linux. See :issue:`1569`.

• Make zope.interface, zope.event and (by extension) setuptools required dependencies. The events install extra now does nothing and will be removed in 2021. See :issue:`1619`.

• Update bundled libuv from 1.36.0 to 1.38.0. See :issue:`1621`.

• Update bundled c-ares from 1.16.0 to 1.16.1.

  On macOS, stop trying to adjust c-ares headers to make them universal. See :issue:`1624`.

• Make gevent locks that are monkey-patched usually work across native threads as well as across greenlets within a single thread. Locks that are only used in a single thread do not take a performance hit. While cross-thread locking is relatively expensive, and not a recommended programming pattern, it can happen unwittingly, for example when using the threadpool and logging.

  Before, cross-thread lock uses might succeed, or, if the lock was contended, raise greenlet.error. Now, in the contended case, if the lock has been acquired by the main thread at least once, it should correctly block in any thread, cooperating with the event loop of both threads. In certain (hopefully rare) cases, it might be possible for contended case to raise LoopExit when previously it would have raised greenlet.error; if these cases are a practical concern, please open an issue.

  Also, the underlying Semaphore always behaves in an atomic fashion (as if the GIL was not released) when PURE_PYTHON is set. Previously, it only correctly did so on PyPy. See :issue:`1437`.

• Rename gevent's C accelerator extension modules using a prefix to avoid clashing with other C extensions. See :issue:`1480`.

• Using gevent.wait on an Event more than once, when that Event is already set, could previously raise an AssertionError.

  As part of this, exceptions raised in the main greenlet will now include a more complete traceback from the failing greenlet. See :issue:`1540`.

• Avoid closing the same Python libuv watcher IO object twice. Under some circumstances (only seen on Windows), that could lead to program crashes. See :issue:`1587`.

• gevent can now be built using Cython 3.0a5 and newer. The PyPI distribution uses this version.

  The libev extension was incompatible with this. As part of this, certain internal, undocumented names have been changed.

  (Technically, gevent can be built with Cython 3.0a2 and above. However, up through 3.0a4 compiling with Cython 3 results in gevent's test for memory leaks failing. See this Cython issue.) See :issue:`1599`.

• Destroying a hub after joining it didn't necessarily clean up all resources associated with the hub, especially if the hub had been created in a secondary thread that was exiting. The hub and its parent greenlet could be kept alive.

  Now, destroying a hub drops the reference to the hub and ensures it cannot be switched to again. (Though using a new blocking API call may still create a new hub.)

  Joining a hub also cleans up some (small) memory resources that might have stuck around for longer before as well. See :issue:`1601`.

• Fix some potential crashes under libuv when using gevent.signal_handler. The crashes were seen running the test suite and were non-deterministic. See :issue:`1606`.

• Update bundled c-ares to version 1.16.0. Changes. See :issue:`1588`.
• Update all the bundled config.guess and config.sub scripts. See :issue:`1589`.
• Update bundled libuv from 1.34.0 to 1.36.0. See :issue:`1597`.

• Use ares_getaddrinfo instead of a manual lookup.

  This requires c-ares 1.16.0.

  Note that this may change the results, in particular their order.

  As part of this, certain parts of the c-ares extension were adapted to use modern Cython idioms.

  A few minor errors and discrepancies were fixed as well, such as gethostbyaddr('localhost') working on Python 3 and failing on Python 2. The DNSpython resolver now raises the expected TypeError in more cases instead of an AttributeError. See :issue:`1012`.

• The c-ares and DNSPython resolvers now raise exceptions much more consistently with the standard resolver. Types and errnos are substantially more likely to match what the standard library produces.

  Depending on the system and configuration, results may not match exactly, at least with DNSPython. There are still some rare cases where the system resolver can raise herror but DNSPython will raise gaierror or vice versa. There doesn't seem to be a deterministic way to account for this. On PyPy, getnameinfo can produce results when CPython raises socket.error, and gevent's DNSPython resolver also raises socket.error.

  In addition, several other small discrepancies were addressed, including handling of localhost and broadcast host names.

  Note

  This has been tested on Linux (CentOS and Ubuntu), macOS, and Windows. It hasn't been tested on other platforms, so results are unknown for them. The c-ares support, in particular, is using some additional socket functions and defines. Please let the maintainers know if this introduces issues.

  See :issue:`1459`.

• Let CI (Travis and Appveyor) build and upload release wheels for Windows, macOS and manylinux. As part of this, (a subset of) gevent's tests can run if the standard library's test.support module has been stripped. See :issue:`1555`.
• Update tested PyPy version from 7.2.0 on Windows to 7.3.1. See :issue:`1569`.

• Fix a spurious warning about watchers and resource leaks on libuv on Windows. Reported by Stéphane Rainville. See :issue:`1564`.
• Make monkey-patching properly remove select.epoll and select.kqueue. Reported by Kirill Smelkov. See :issue:`1570`.
• Make it possible to monkey-patch :mod:`contextvars` before Python 3.7 if a non-standard backport that uses the same name as the standard library does is installed. Previously this would raise an error. Reported by Simon Davy. See :issue:`1572`.
• Fix destroying the libuv default loop and then using the default loop again. See :issue:`1580`.
• libuv loops that have watched children can now exit. Previously, the SIGCHLD watcher kept the loop alive even if there were no longer any watched children. See :issue:`1581`.

• PyPy no longer uses the Python allocation functions for libuv and libev allocations. See :issue:`1569`.

• See :issue:`1367`.