Signed-off-by: Anders Kaseorg <anders@zulip.com>

We previously forked tornado.autoreload to work around a problem where
it would crash if you introduce a syntax error and not recover if you
fix it (tornadoweb/tornado#2398).

A much more maintainable workaround for that issue, at least in
current Tornado, is to use tornado.autoreload as the main module.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

Signed-off-by: Anders Kaseorg <anders@zulip.com>

IOLoop.set_blocking_log_threshold and IOLoop.handle_callback_exception
are removed in Tornado 6.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

Signed-off-by: Anders Kaseorg <anders@zulip.com>

Signed-off-by: Anders Kaseorg <anders@zulip.com>

Signed-off-by: Anders Kaseorg <anders@zulip.com>

According to the documentation: “Pika does not have any notion of
threading in the code. If you want to use Pika with threading, make
sure you have a Pika connection per thread, created in that thread. It
is not safe to share one Pika connection across threads, with one
exception: you may call the connection method add_callback_threadsafe
from another thread to schedule a callback within an active pika
connection.”

https://pika.readthedocs.io/en/stable/faq.html

This also means that synchronous Django code running in Tornado will
use its own synchronous SimpleQueueClient rather than sharing the
asynchronous TornadoQueueClient, which is unfortunate but necessary as
they’re about to be on different threads.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

Signed-off-by: Anders Kaseorg <anders@zulip.com>

Signed-off-by: Anders Kaseorg <anders@zulip.com>

Fixes zulip#8913.

Signed-off-by: Anders Kaseorg <anders@zulip.com>