A video's preview and a picture's thumbnail are made inside the request that posts the message, and
nothing bounded how long either could take.
- The video preview filter also selects any frame from 5 seconds on. Rails' filter takes the second
frame it selects, which a video with a single keyframe and no scene change only gives at its end, so
ffmpeg decoded all of it.
- TimeLimitedVideoPreviewer gives ffmpeg 10 seconds of wall-clock time, kills it past that, and reports
a failed preview, so the message is posted without one.
- Pictures and videos above 250 megapixels, or whose size couldn't be read, get no preview: decoding
costs in proportion to the pixels, however small the file.
- The view shows a preview only if it was made when the message was posted. Its URL used to make it on
view, so a preview that failed or was skipped would be attempted again on every view. The cached
presentation's version goes up, so cached messages pick this up.
- A video's poster is made, when the message is posted, at the size the view shows it. The full-size WebP
made until now wasn't shown anywhere, and encoding it costs in proportion to the frame's pixels.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bj8KnxpTf9sj2Ysa8aLAVa
Pages of messages load them with_presentation, which preloads each
message's boosts with their boosters and avatars, but the boosts partial
asked for message.boosts.ordered: a new query for every message, and the
preloaded boosts went unused. Sort the preloaded boosts in Ruby. The
boosts frame, whose message comes without them, still queries them in
order with their boosters.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0142qgjggdJ2KDdGk7RF9Xm9
Every boost had its own fragment, nested inside the message fragment that
already holds it. With a cold cache, a read and a write per boost plus a
read_multi and a write_multi per message: a room page of 40 messages with
120 boosts takes ~410 ms instead of ~290 ms. Redis runs without persistence
(config/redis.conf), so every page is cold after a restart.
A boost touches its message, so adding or removing one rewrites the message
fragment anyway. The inner fragments only paid off when a message with many
boosts was drawn again, and there they hid a lookup per booster. The boosters
are now loaded with the boosts, one query per message.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0142qgjggdJ2KDdGk7RF9Xm9
* Preload only uncached messages and reduce rendering overhead
* Keep benchmark summaries without raw JSON results
* Use Ruby benchmark drivers and keep generated results out of the repo
GPT on behalf of DHH
Marcello Costagliola
David Heinemeier Hansson