Can someone link to the full resolution final image? Been trying to find it. Thanks!
This is the final bitmap. http://i.imgur.com/ajWiAYi.png
How We Built r/Place
21–30 of 255 posts
Re: How We Built r/Place
#22Earlier quoted context omitted.
If you ever want to revisit, it's linked in the right side of the sub. https://www.reddit.com/place?webview=true
For some reason it leads to 403...weird
http://i.imgur.com/dYdHDYe.png
I've exported it to imgur for you.
Re: How We Built r/Place
#23r/Place is really awesome. This is how you grow the community. The 2D and 3D timelapses are super cool to watch, as well. Glad Reddit decided to make this a full-time thing.
Re: How We Built r/Place
#24Thank you for the fascinating writeup! How long did the whole thing take to put together?
First commit was on Jan 20 [0], so that provides a lower-bound for how long they spent on it.
[0] - https://github.com/reddit/reddit-plugin-place-opensource/com...
Re: How We Built r/Place
#25> We actually had a race condition here that allowed users to place multiple tiles at once. There was no locking around the steps 1-3 so simultaneous tile draw attempts could all pass the check at step 1 and then draw multiple tiles at step 2. This is why you use a proper database. I'd probably add a Postgres table to record all user activity, and use that to lock out users for 5 minutes as an initial filter. Have tr…
And what about adding a million rows to the RDBMS and querying it in under 100ms (which Redis allowed them to do).
I will say that it was an implementation bug which doesn't warrant the swapping out of entire data storage layers.
Re: How We Built r/Place
#26> Users can place one tile every 5 minutes, so we must support an average update rate of 100,000 tiles per 5 minutes (333 updates/s). It only takes a couple of outliers to bring everything down. I'm not exactly well-versed in defining specs for large scale backend apps (not a back-end engineer) but it seems to me that preparing for the average would not be a wise decision? For example, designing with an average of a…
I can shed that 333 [something/s], for any uncomplicated something, is so little that a single-core 10YO laptop running a single-process non-blocking webserver (a-la node) could probably handle it, and likely x10 it.
Re: How We Built r/Place
#27Earlier quoted context omitted.
The entire reddit website goes down every night, especially during weekends, sport matches, etc, so there you have your answer.
Is that hyperbole or are you really experiencing that much downtime of Reddit? I see it occasionally but it's never down for long, the odd "servers are busy" message usually disappears after a single refresh.
Pages take a long time to generate all day, but during peak hours they take a minimum of 4 seconds each (depends on what page you're loading, if it's got lots of comments, etc), and many times they simply timeout. The engineers at reddit have been unable thus far to fix it.
Re: How We Built r/Place
#28Now I'm curious, Are there any websites that do something similar to /r/place? (hackathon idea?)
Also, reminds be of the million dollar front page [1].
[1] https://en.wikipedia.org/wiki/The_Million_Dollar_Homepage
Re: How We Built r/Place
#29> We actually had a race condition here that allowed users to place multiple tiles at once. There was no locking around the steps 1-3 so simultaneous tile draw attempts could all pass the check at step 1 and then draw multiple tiles at step 2. This is why you use a proper database. I'd probably add a Postgres table to record all user activity, and use that to lock out users for 5 minutes as an initial filter. Have tr…
So in that case, each pixel would be stored as a separate row in a relational database? And to query the whole canvas you'd query a million rows on every read? I lean towards just using the ratelimiting stuff we already have in place (via memcached, which we talked about in a previous post). We just overlooked it.
> And to query the whole canvas you'd query a million rows on every read?
No, just using it to store the update log.
But I don't know if there's any obvious problem with querying a handful of megabytes once per second either.
Re: How We Built r/Place
#30> We actually had a race condition here that allowed users to place multiple tiles at once. There was no locking around the steps 1-3 so simultaneous tile draw attempts could all pass the check at step 1 and then draw multiple tiles at step 2. This is why you use a proper database. I'd probably add a Postgres table to record all user activity, and use that to lock out users for 5 minutes as an initial filter. Have tr…
So in that case, each pixel would be stored as a separate row in a relational database? And to query the whole canvas you'd query a million rows on every read? I lean towards just using the ratelimiting stuff we already have in place (via memcached, which we talked about in a previous post). We just overlooked it.
I'd most likely have two tables - one for user activity and one for each pixel (1 million rows only in that table). Selecting a million rows from that pixel table might be 200ms or whatever. I'd still have Redis cache, though, since you're getting 100ms.