Zulip has had a small use of WebSockets (specifically, for the code
path of sending messages, via the webapp only) since ~2013. We
originally added this use of WebSockets in the hope that the latency
benefits of doing so would allow us to avoid implementing a markdown
local echo; they were not. Further, HTTP/2 may have eliminated the
latency difference we hoped to exploit by using WebSockets in any
case.
While we’d originally imagined using WebSockets for other endpoints,
there was never a good justification for moving more components to the
WebSockets system.
This WebSockets code path had a lot of downsides/complexity,
including:
* The messy hack involving constructing an emulated request object to
hook into doing Django requests.
* The `message_senders` queue processor system, which increases RAM
needs and must be provisioned independently from the rest of the
server).
* A duplicate check_send_receive_time Nagios test specific to
WebSockets.
* The requirement for users to have their firewalls/NATs allow
WebSocket connections, and a setting to disable them for networks
where WebSockets don’t work.
* Dependencies on the SockJS family of libraries, which has at times
been poorly maintained, and periodically throws random JavaScript
exceptions in our production environments without a deep enough
traceback to effectively investigate.
* A total of about 1600 lines of our code related to the feature.
* Increased load on the Tornado system, especially around a Zulip
server restart, and especially for large installations like
zulipchat.com, resulting in extra delay before messages can be sent
again.
As detailed in
https://github.com/zulip/zulip/pull/12862#issuecomment-536152397, it
appears that removing WebSockets moderately increases the time it
takes for the `send_message` API query to return from the server, but
does not significantly change the time between when a message is sent
and when it is received by clients. We don’t understand the reason
for that change (suggesting the possibility of a measurement error),
and even if it is a real change, we consider that potential small
latency regression to be acceptable.
If we later want WebSockets, we’ll likely want to just use Django
Channels.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
Previous cleanups (mostly the removals of Python __future__ imports)
were done in a way that introduced leading newlines. Delete leading
newlines from all files, except static/assets/zulip-emoji/NOTICE,
which is a verbatim copy of the Apache 2.0 license.
Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
As part of our effort to change the data model away from each user
having a single API key, we're eliminating the couple requests that
were made from Django to Tornado (as part of a /register or home
request) where we used the user's API key grabbed from the database
for authentication.
Instead, we use the (already existing) internal_notify_view
authentication mechanism, which uses the SHARED_SECRET setting for
security, for these requests, and just fetch the user object using
get_user_profile_by_id directly.
Tweaked by Yago to include the new /api/v1/events/internal endpoint in
the exempt_patterns list in test_helpers, since it's an endpoint we call
through Tornado. Also added a couple missing return type annotations.
We only use this in the direct management command, and it involves
some autoreload process setup stuff that we probably don't want to do
in our unit tests regardless.
Tornado reloads the app whenever there is a change in code. Due to this,
new connection is created to the client which also results in a new
channel. To avoid creating two channels for the queue in the RabbitMQ
broker we should close the old channel. Otherwise messages sent to the
queue will be distributed among these two channels in a round robin
scheme and we will end up losing one message since one of the channels
doesn't have an active consumer.
This commit closes the connection to the queue whenever Tornado reloads
the application using add_reload_hook().
Fixes#5824.
This fixes an issue where if you saved a Python file (even just
changing whitespace) while casper tests were running, the Tornado
server being used would restart, triggering a confusing error like
this:
ReferenceError: Can't find variable: $
Traceback:
undefined:2
:4
Suite explicitly interrupted without any message given.
Anders Kaseorg
Anders Kaseorg
Tim Abbott
rht
Umair Khan
AZtheAsian