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How Facebook's Safety Check Works

highscalability.com

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41–50 of 52 posts

Re: How Facebook's Safety Check Works

#41

Post by eggie »

fnbr wrote: post #27
haraldurt wrote: post #20

>The average distance between any two of Facebook’s 1.5 billion users is 4.74 edges. Sorry Kevin. With 1.5 billion users the whole graph can be explored within 5 hops. Nitpicking here, but that does not follow. Starting from a random user and hopping 5 times in all directions you'd expect to explore about half of the graph.

Your post is technically correct, but I think that you'd be likelier to explore more- say, 80% of the graph. I suspect that there are small pockets of extremely unconnected people which creates a long tail, distorting the mean.

Unless the data can somehow be shared how is anyone to know what the structure is? There is no point in speculating...

Re: How Facebook's Safety Check Works

#42

Post by eggie »

omginternets wrote: post #31
rmc wrote: post #29

Earlier quoted context omitted.

The real reason, which they probably can't say, is how much media attention it gets in the USA.

I'm entertaining the notion that this is a way to justify some new privacy-invading feature. I'd love to be wrong, and I'm open to a statement from a FB employee, if such a thing were possible.

Or perhaps it motivates the idea that if you do not use facebook you can never be completely "safe".

Re: How Facebook's Safety Check Works

#43

Post by ma2rten »

xxbondsxx wrote: post #6

Hey everyone! FB engineer here who wrote the original code for this and gave the talk during @Scale 2015. There's a recording of our talk here: https://youtu.be/ptsCWGZW_P8?t=333 That's a bit more visual and easier to understand. At the end of the day its really just DFS with seen state and selective exploration :)

Sorry, I don't have time to see the video right now, but I am wondering if it isn't possible for you to use something like Hadoop/Hive/Presto to simply get a list of all users in Paris on demand.

Re: How Facebook's Safety Check Works

#44

Post by mason55 »

jonesb6 wrote: post #39
mason55 wrote: post #19

Earlier quoted context omitted.

Generally people are ok with Facebook doing it because they can opt out. If you notice, the times people really get upset about companies tracking their personal information is if it's either not disclosed or it's done in a shady manner. Also, capitalist societies tend to treat state actors differently than private corporations. It's much easier to choose a new corporation to interact with and the state tends to have…

Yeah ok but how many end-users are conscious enough of the situation to OPT-OUT of such an intrusive policy? On the same vein as accepting every terms and conditions that comes your way, I think most people are severely uninformed about this. It's like how many people believe software engineering is "magic", they believe Facebook or the government will protect them with "magic". Hint: there is no magic.

> Yeah ok but how many end-users are conscious enough of the situation to OPT-OUT of such an intrusive policy?

Well, I meant opt-out as in "not use". Plenty of people don't use Facebook because of the privacy implications. And as another use mentioned, this is the reason that people are so upset about Facebook's shadow profiles, because it removed your ability to opt out of their tracking.

Re: How Facebook's Safety Check Works

#45

Post by konstruktor »

TeMPOraL wrote: post #21
konstruktor wrote: post #14

Earlier quoted context omitted.

If the safety of your products depends on disabling features, you should stay out of anything remotely safety critical.

What the hell, this can be said about anything. As GP provides an example for, even an unexpected phone call can be unsafe.

In my opinion, "other things are just as bad" is as good an argument as "if you turn it off, it's not dangerous".

I still think it's not smart to send push notifications in an active shooter situation for a feature that is made to give people who are not involved peace of mind. If you consider such risks, and not get defensive right away, you will find that solutions can be pretty simple, e.g. a banner inside the app, instead of a notification.

Re: How Facebook's Safety Check Works

#46

Post by flashman »

I wonder what Facebook will say when the governments of the world realise they can use this capability to contact their own citizens - especially if Facebook's continued operation in that country is contingent on its cooperation.

'Safety Check' is just the end user experience; the underlying mechanism is a way to propagate messages invasively across a geo-social network. Like any technology, 'good' or 'nasty' depends on how it's used.

Re: How Facebook's Safety Check Works

#47

Post by xxbondsxx »

ma2rten wrote: post #43
xxbondsxx wrote: post #6

Hey everyone! FB engineer here who wrote the original code for this and gave the talk during @Scale 2015. There's a recording of our talk here: https://youtu.be/ptsCWGZW_P8?t=333 That's a bit more visual and easier to understand. At the end of the day its really just DFS with seen state and selective exploration :)

Sorry, I don't have time to see the video right now, but I am wondering if it isn't possible for you to use something like Hadoop/Hive/Presto to simply get a list of all users in Paris on demand.

Hive and Hadoop are offline -- it can take ~45 minutes to execute a query on our entire user table (even longer if it involves joins) and certain times of the day its slower (during work hours usually). Not only that, but once the query executes some engineer has to go copy and paste into a script that would likely run on one machine.

Doing this in a distributed async job fashion allowed for a lot more flexibility. Even better, we can even change the geographic area as the algorithm runs and those changes are reflected immediately.

Re: How Facebook's Safety Check Works

#48

Post by xxbondsxx »

flashman wrote: post #46

I wonder what Facebook will say when the governments of the world realise they can use this capability to contact their own citizens - especially if Facebook's continued operation in that country is contingent on its cooperation. 'Safety Check' is just the end user experience; the underlying mechanism is a way to propagate messages invasively across a geo-social network. Like any technology, 'good' or 'nasty' depends…

Usually this is enforced at the cellphone carrier level. The US has the amber alert protocol which also has a function for the president to dispatch any message (and can only be used by the president iirc), and that level of message can't be turned off via settings.

Even in our best countries FB usage is never 100%, so cellphone / landlines makes a bit more sense.

Re: How Facebook's Safety Check Works

#49

Post by dragonwriter »

xxbondsxx wrote: post #48
flashman wrote: post #46

I wonder what Facebook will say when the governments of the world realise they can use this capability to contact their own citizens - especially if Facebook's continued operation in that country is contingent on its cooperation. 'Safety Check' is just the end user experience; the underlying mechanism is a way to propagate messages invasively across a geo-social network. Like any technology, 'good' or 'nasty' depends…

Usually this is enforced at the cellphone carrier level. The US has the amber alert protocol which also has a function for the president to dispatch any message (and can only be used by the president iirc), and that level of message can't be turned off via settings. Even in our best countries FB usage is never 100%, so cellphone / landlines makes a bit more sense.

> The US has the amber alert protocol which also has a function for the president to dispatch any message (and can only be used by the president iirc), and that level of message can't be turned off via settings.

This is the Wireless Emergency Alert system, which carries Amber Alerts, Alerts about imminent threats to life/safety, and Presidential Alerts. The last (and only the last) can't be disabled in settings, because the legislation requiring support for the capacity required that Presidential alerts not be disabled. (The system is basically the mobile-device equivalent of the broadcast Emergency Alert System.)

Re: How Facebook's Safety Check Works

#50

Post by TeMPOraL »

konstruktor wrote: post #45
TeMPOraL wrote: post #21

Earlier quoted context omitted.

What the hell, this can be said about anything. As GP provides an example for, even an unexpected phone call can be unsafe.

In my opinion, "other things are just as bad" is as good an argument as "if you turn it off, it's not dangerous". I still think it's not smart to send push notifications in an active shooter situation for a feature that is made to give people who are not involved peace of mind. If you consider such risks, and not get defensive right away, you will find that solutions can be pretty simple, e.g. a banner inside the app…

I think shooting was aready over before people over at Facebook even knew something is going on. I imagine they wouldn't even turn it on before the information hit mainstream news.
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