Stopping and restarting a proactor event loop on windows can lead to
spurious errors logged (ConnectionResetError while reading from the
self pipe). This fixes the issue by ensuring that we don't attempt
to start multiple copies of the self-pipe reading loop.
* bpo-41273: Proactor transport read loop to use recv_into
By using recv_into instead of recv we do not allocate a new buffer each
time _loop_reading calls recv.
This betters performance for any stream using proactor (basically any
asyncio stream on windows).
* bpo-41273: Double proactor read transport buffer size
By doubling the read buffer size we get better performance.
Capturing exceptions into names can lead to reference cycles though the __traceback__ attribute of the exceptions in some obscure cases that have been reported previously and fixed individually. As these variables are not used anyway, we can remove the binding to reduce the chances of creating reference cycles.
See for example GH-13135
This will address the common mistake many asyncio users make:
an "except Exception" clause breaking Tasks cancellation.
In addition to this change, we stop inheriting asyncio.TimeoutError
and asyncio.InvalidStateError from their concurrent.futures.*
counterparts. There's no point for these exceptions to share the
inheritance chain.
In 3.9 we'll focus on implementing supervisors and cancel scopes,
which should allow better handling of all exceptions, including
SystemExit and KeyboardInterrupt
asyncio.ProactorEventLoop now catchs and logs send errors when the
self-pipe is full: BaseProactorEventLoop._write_to_self() now catchs
and logs OSError exceptions, as done by
BaseSelectorEventLoop._write_to_self().
* asyncio: __del__() keep reference to warnings.warn
The __del__() methods of asyncio classes now keep a strong reference
to the warnings.warn() to be able to display the ResourceWarning
warning in more cases. Ensure that the function remains available if
instances are destroyed late during Python shutdown (while module
symbols are cleared).
* Rename warn parameter to _warn
"_warn" name is a hint that it's not the regular warnings.warn()
function.
bpo-32622, bpo-35682: Fix asyncio.ProactorEventLoop.sendfile(): don't
attempt to set the result of an internal future if it's already done.
Fix asyncio _ProactorBasePipeTransport._force_close(): don't set the
result of _empty_waiter if it's already done.
The cancellation of an overlapped WSARecv() has a race condition
which causes data loss because of the current implementation of
proactor in asyncio.
No longer cancel overlapped WSARecv() in _ProactorReadPipeTransport
to work around the race condition.
Remove the optimized recv_into() implementation to get simple
implementation of pause_reading() using the single _pending_data
attribute.
Move _feed_data_to_bufferred_proto() to protocols.py.
Remove set_protocol() method which became useless.
In this commit:
* Support BufferedProtocol in set_protocol() and start_tls()
* Fix proactor to cancel readers reliably
* Update tests to be compatible with OpenSSL 1.1.1
* Clarify BufferedProtocol docs
* Bump TLS tests timeouts to 60 seconds; eliminate possible race from start_serving
* Rewrite test_start_tls_server_1
The proactor event loop has a race condition when reading with
pausing/resuming. `resume_reading()` unconditionally schedules the read
function to read from the current future. If `resume_reading()` was
called before the previously scheduled done callback fires, this results
in two attempts to get the data from the most recent read and an
assertion failure. This commit tracks whether or not `resume_reading`
needs to reschedule the callback to restart the loop, preventing a
second attempt to read the data.
* Make ssh_handshake_timeout None by default.
* Raise ValueError if ssl_handshake_timeout is used without ssl.
* Raise ValueError if ssl_handshake_timeout is not positive.
Issue #26604:
* Add a new optional source parameter to _warnings.warn() and warnings.warn()
* Modify asyncore, asyncio and _pyio modules to set the source parameter when
logging a ResourceWarning warning
getaddrinfo takes an exclusive lock on some platforms, causing clients to queue
up waiting for the lock if many names are being resolved concurrently. Users
may want to handle name resolution in their own code, for the sake of caching,
using an alternate resolver, or to measure DNS duration separately from
connection duration. Skip getaddrinfo if the "host" passed into
create_connection is already resolved.
See https://github.com/python/asyncio/pull/302 for details.
Patch by A. Jesse Jiryu Davis.
