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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> |
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| .. | ||
| ci | ||
| circleci | ||
| documentation_crawler | ||
| droplets | ||
| i18n | ||
| lib | ||
| linter_lib | ||
| setup | ||
| test-install | ||
| tests | ||
| zulip-export | ||
| __init__.py | ||
| build-docs | ||
| build-release-tarball | ||
| cache-zulip-git-version | ||
| check-capitalization | ||
| check-frontend-i18n | ||
| check-issue-labels | ||
| check-openapi | ||
| check-provision | ||
| check-templates | ||
| clean-branches | ||
| clean-repo | ||
| commit-message-lint | ||
| commit-msg | ||
| conf.ini-template | ||
| coveragerc | ||
| create-test-api-docs | ||
| deploy-branch | ||
| diagnose | ||
| django-template-graph | ||
| do-destroy-rebuild-database | ||
| do-destroy-rebuild-test-database | ||
| documentation.vnufilter | ||
| fetch-pull-request | ||
| fetch-rebase-pull-request | ||
| find-unused-css | ||
| get-handlebar-vars | ||
| html-grep | ||
| js-dep-visualizer.py | ||
| lint | ||
| pre-commit | ||
| pretty-print-html | ||
| provision | ||
| push-to-pull-request | ||
| README.md | ||
| release-tarball-exclude.txt | ||
| renumber-migrations | ||
| replacer | ||
| reset-to-pull-request | ||
| review | ||
| run-dev.py | ||
| run-mypy | ||
| run-tsc | ||
| run-yarn-deduplicate | ||
| setup-git-repo | ||
| show-profile-results | ||
| stop-run-dev | ||
| test-all | ||
| test-api | ||
| test-backend | ||
| test-documentation | ||
| test-emoji-name-scripts | ||
| test-help-documentation | ||
| test-js-with-casper | ||
| test-js-with-node | ||
| test-locked-requirements | ||
| test-migrations | ||
| test-queue-worker-reload | ||
| test-run-dev | ||
| test-tools | ||
| update-authors-json | ||
| update-locked-requirements | ||
| update-prod-static | ||
| update-zuliprc-api-field | ||
| webpack | ||
| webpack-helpers.ts | ||
| webpack.assets.json | ||
| webpack.config.ts | ||
| zanitizer | ||
| zanitizer_config.pm.sample | ||
This directory contains scripts that are used in building, managing,
testing, and other forms of work in a Zulip development environment.
Note that tools that are also useful in production belong in
scripts/ or should be Django management commands.
For more details, see https://zulip.readthedocs.io/en/latest/overview/directory-structure.html.