1.4.6 (Apr 2, 2019)

This is a patch release primarily focused on bugs related to concurrency,
SSL connections and testing, and SASL authentication.
Major thanks to @pt2pham , @isamaru , @braedon , @gingercookiemage , for submitting
PRs to help fix many of these issues. And major thanks to everyone that
submitted bug reports and issues. And thanks always to @jeffwidman and @tvoinarovskyi for code
reviews, comments, testing, debugging, and helping to maintain this project!

Client Concurrency Issues (Race Conditions / Deadlocks)

• Fix race condition in protocol.send_bytes (isamaru / PR #1752)
• Do not call state_change_callback with lock (dpkp / PR #1775)
• Additional BrokerConnection locks to synchronize protocol/IFR state (dpkp / PR #1768)
• Send pending requests before waiting for responses (dpkp / PR #1762)
• Avoid race condition on client._conns in send() (dpkp / PR #1772)
• Hold lock during client.check_version (dpkp / PR #1771)

Producer Wakeup / TimeoutError

• Dont wakeup during maybe_refresh_metadata -- it is only called by poll() (dpkp / PR #1769)
• Dont do client wakeup when sending from sender thread (dpkp / PR #1761)

SSL - Python3.7 Support / Bootstrap Hostname Verification / Testing

• Wrap SSL sockets after connecting for python3.7 compatibility (dpkp / PR #1754)
• Allow configuration of SSL Ciphers (dpkp / PR #1755)
• Maintain shadow cluster metadata for bootstrapping (dpkp / PR #1753)
• Generate SSL certificates for local testing (dpkp / PR #1756)
• Rename ssl.keystore.location and ssl.truststore.location config files (dpkp)
• Reset reconnect backoff on SSL connection (dpkp / PR #1777)

SASL - OAuthBearer support / api version bugfix

• Fix 0.8.2 protocol quick detection / fix SASL version check (dpkp / PR #1763)
• Update sasl configuration docstrings to include supported mechanisms (dpkp)
• Support SASL OAuthBearer Authentication (pt2pham / PR #1750)

Miscellaneous Bugfixes

• Dont force metadata refresh when closing unneeded bootstrap connections (dpkp / PR #1773)
• Fix possible AttributeError during conn._close_socket (dpkp / PR #1776)
• Return connection state explicitly after close in connect() (dpkp / PR #1778)
• Fix flaky conn tests that use time.time (dpkp / PR #1758)
• Add py to requirements-dev (dpkp)
• Fixups to benchmark scripts for py3 / new KafkaFixture interface (dpkp)