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Chess.com stopped working on 32bit iPads because 2^31 games have been played

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Re: Chess.com stopped working on 32bit iPads because 2^31 games have been played

#61

Post by moufestaphio »

sbov wrote: post #46
glhaynes wrote: post #34

Earlier quoted context omitted.

Similar to how much effort goes into dealing with things like dangerous strains of bird flu, only to have people complain about how much money was spent on "nothing" when an outbreak doesn't occur.

This is a whole class of problem - I wonder if there's a name for it. More examples include: talking about welfare being unnecessary because no one is starving. Or people on medications stopping because they feel better (while still on them).

Like when people say to IT: "Everything's working, what am I playing you for?!"

Re: Chess.com stopped working on 32bit iPads because 2^31 games have been played

#62

Post by justin66 »

wpietri wrote: post #56
justin66 wrote: post #36

Earlier quoted context omitted.

> I sometimes think it would've been better if a few things had visibly failed in January 2000. Having to spend billions of dollars on programmers' goofy means of saving a few bytes of memory is a pretty visible failure.

Nope. Definitely not goofy. My dad was a programmer in the early days. The machines he started on in the 1960s had 8 KB of RAM. Saving a byte then is the equivalent today of saving 1 MB on an 8 GB machine. Multiply that times, say, the thousands of customer orders you're trying to process and the goofy thing would be burning a lot of additional RAM because it might help somebody 35 years later. Who among us is writin…

- Who among us is writing code today worried about how it will be used in 2052?

The good programmers who are fortunate enough to be working on software that matters.

Re: Chess.com stopped working on 32bit iPads because 2^31 games have been played

#63

Post by nisse72 »

vxxzy wrote: post #3

How many other examples like this have occurred throughout computing history?

IP4 address space comes to mind.

And I think it isn't uncommon to have to add digits to the front of telephone numbers as regions grow (or telephones become more common) and the number space isn't large enough.

Re: Chess.com stopped working on 32bit iPads because 2^31 games have been played

#64

Post by davidgerard »

justin66 wrote: post #62
wpietri wrote: post #56

Earlier quoted context omitted.

Nope. Definitely not goofy. My dad was a programmer in the early days. The machines he started on in the 1960s had 8 KB of RAM. Saving a byte then is the equivalent today of saving 1 MB on an 8 GB machine. Multiply that times, say, the thousands of customer orders you're trying to process and the goofy thing would be burning a lot of additional RAM because it might help somebody 35 years later. Who among us is writin…

- Who among us is writing code today worried about how it will be used in 2052? The good programmers who are fortunate enough to be working on software that matters.

In my experience it's not the good systems that stick around - they're cleanly replaceable.

It's the quick hacks and bodges that stick around forever.

Re: Chess.com stopped working on 32bit iPads because 2^31 games have been played

#65

Post by cvoss »

dpark wrote: post #52
MereInterest wrote: post #45

Earlier quoted context omitted.

Assuming you're working in a language that defines signed integer overflow. Depending on the language, you can result in undefined behavior, instead. For that reason, I'd go with an unsigned counter, with the first million IDs being invalid or reserved for future use. That way, you get well-defined overflow into an invalid region.

When's the last time you worked with an architecture that didn't use twos complement and roll into negatives on overflow? Your reserved bottom range is a perfectly good solution. But rolling into negatives seems fine, too.

C/C++ is notoriously head-ache inducing on this point. Yes, all the CPU archs you'd reasonably expect to encounter today behave this way. However, because the language standard says signed overflow is undefined, compilers are free to assume that it will never happen, and make optimizations that you'd think would be unsafe, but are technically permissible. [1]

[1]https://stackoverflow.com/questions/18195715/why-is-unsigned...

Re: Chess.com stopped working on 32bit iPads because 2^31 games have been played

#66

Post by relyio »

chesserik wrote: post #54

Hey all. Thanks for noticing :P Obviously this is embarrassing and I'm sorry about it. As a non-developer I can't really explain how or why this happened, but I can say that we do our best and are sorry when that falls short. - Erik, CEO, Chess.com

It's an honest mistake, things like this happen. Not the end of the world, especially for an otherwise great product like chess.com.

Go easy on your eng team ;)

Re: Chess.com stopped working on 32bit iPads because 2^31 games have been played

#67

Post by [deleted] »

zokier wrote: post #59
dpark wrote: post #52

Earlier quoted context omitted.

When's the last time you worked with an architecture that didn't use twos complement and roll into negatives on overflow? Your reserved bottom range is a perfectly good solution. But rolling into negatives seems fine, too.

Signed overflow is ub in C

[deleted]

Re: Chess.com stopped working on 32bit iPads because 2^31 games have been played

#68

Post by mistersquid »

sbov wrote: post #46
glhaynes wrote: post #34

Earlier quoted context omitted.

Similar to how much effort goes into dealing with things like dangerous strains of bird flu, only to have people complain about how much money was spent on "nothing" when an outbreak doesn't occur.

This is a whole class of problem - I wonder if there's a name for it. More examples include: talking about welfare being unnecessary because no one is starving. Or people on medications stopping because they feel better (while still on them).

I think this is actually a version of confirmation bias since

  > Confirmation bias, also known as Observational selection or The enumeration of
  > favorable circumstances is the tendency for people to (consciously or
  > unconsciously) seek out information that conforms to their pre-existing view
  > points, and subsequently ignore information that goes against them, both
  > positive and negative [0]
[0] http://rationalwiki.org/wiki/Confirmation_bias

Re: Chess.com stopped working on 32bit iPads because 2^31 games have been played

#69

Post by dpark »

zokier wrote: post #59
dpark wrote: post #52

Earlier quoted context omitted.

When's the last time you worked with an architecture that didn't use twos complement and roll into negatives on overflow? Your reserved bottom range is a perfectly good solution. But rolling into negatives seems fine, too.

Signed overflow is ub in C

I'm aware of that. The question was whether any practical architectures will do the "wrong" thing here.

Re: Chess.com stopped working on 32bit iPads because 2^31 games have been played

#70

Post by windowshopping »

chesserik wrote: post #54

Hey all. Thanks for noticing :P Obviously this is embarrassing and I'm sorry about it. As a non-developer I can't really explain how or why this happened, but I can say that we do our best and are sorry when that falls short. - Erik, CEO, Chess.com

We can help you understand how and why!

Computers set limits internally on how big numbers can be when they're keeping track of stuff.

Your developers had given each game a number to identify it. So your first game was #1, the 40th game was #40, and so on.

The limit for how big the number could be was a bit over 2 billion, and your players have just now played a bit over 2 billion games, and so that id number suddenly exceeded the computer's internal limit. Specifically, the limit was 2147483648, so basically it crashed on game #2147483649, which is the next id after the last acceptable one (notice the last digit is 1 higher.)

I'm simplifying slightly but that's the idea. It'll be fixable by essentially using a different format for the id number so that the limit is higher, much like telling the computer "use a higher limit for this particular number, it's special."

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