81–90 of 107 posts
Isn't this referred to as Load Shedding in some circles? If its not, can someone explain how its different?
The situation is that A depends on B, but B is overloaded; if we allow B to do load shedding, we must also write A to gracefully degrade when B is not available.
> if (disableCommentsRanking.enabled == False) This could use some light-touch code reviewing
I'm surprised they don't have automated degradation (or at least the article implies that it must be operator initiated). We built a similar tool at Netflix but the degradations could be both manual and automatic.
The manual part of Defcon is more "holy crap, we lost a datacenter and the whole site is melting, turn stuff off to bring the load down ASAP"
Am I reading the second figure right? Facebook can do 130*10^6 queries/second == 130,000,000 queries/second?!
I think about 10 years ago when I was working there I checked the trace to load my own homepage. Just one page, just for myself, and there were 100,000 data fetches.
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The developer, tester and devops time required to properly implement graceful degradation could easily accumulate to hundreds of hours. Those hours are directly expensive when your developers cost hundreds of dollars a day; and have a material opportunity cost in that their commitment to one particular project delays the delivery of other features. Moreover, any new features would have to be made compatible with the…
Could be as simple as just some feature flags with environment variables
1. It auto restarts all workers in the cluster in "maintenance mode".
2. A "maintenance mode" message shows on the homepage.
3. The top 100 pages by comment volume will still render their comment threads, as a job on each edge node recalculates and stores this on disk periodically.
4. Logging in is disabled.
5. All db calls to the driver are stubbed out with mocks to prevent crashes.
6. Comments can still be posted and are added into an on-disk queue on each edge node.
7. When the system is back online the queue is processed (and stuff checked for spam etc like normal).
It's not perfect but it means in a lot of cases I can completely turn off the DB for a few minutes without panic. I haven't had to use it in over a year, though, and the DB doesn't really go down. But useful for upgrades.
built it on my couch during a Jurassic park marathon :P
> if (disableCommentsRanking.enabled == False) This could use some light-touch code reviewing
Because the HN crowd likes learning new things: if `enabled` is a nullable boolean in C# (i.e. has type `bool?`) then this check must indeed be written this way, to avoid confusing null with false.
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This is how information slowly changes. The original numbers from facebook needed to be taken with a grain of salt. 2 billion a day raises it more. Facebook claims to have 2 billion accounts but no where near 2 billion unique accounts. I don't know what facebook calls an active user but it use to mean logged in once in the past 30 days.
No, the person you're responding to was correct. Facebook has over 2 billion daily active users [1], and DAU refers to unique users who used the product in a day [2]. 1: https://www.statista.com/statistics/346167/facebook-global-d... 2: https://www.innertrends.com/blog/active-users-measuring-busi...
> if (disableCommentsRanking.enabled == False) This could use some light-touch code reviewing
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Could someone tell me what these hundreds of requests could do?
A lot of them appear to be that they've split their javascript into a gazillion files for whatever reason (I suppose because they have several MB of it). But someone or lots of people there did seem to get addicted to dynamic loading. Like I've got 100 or so friends, but my friends page loads them 8-16 at a time as I scroll. Just send all 100 and set the profile pictures to deferred fetch. It'd probably be smaller th…