this post was submitted on 07 Jul 2025
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So, I get that 256 is a base 2 number. But we're not running 8-bit servers or whatever here (and yes, I understand that's not what 8-bit generally refers to). Is there some kind of technical limitation I'm not thinking of where 257 would be any more difficult to implement, or really is it just that 256 has a special place in someone's heart because it's a base 2 number?
Because 256 is exactly one byte. If you want to add a 257th member, you need a whole second byte just for that one person. That's a waste of memory, unless you want to go to the 64k barrier of users per chat.
Except that they're almost certainly just using
int, which is almost certainly at least 32 bits.256 is chosen because the people writing the code are programmers. And just like regular people like multiples of 10, programmers like powers of 2. They feel like nice round numbers.
Well, no. They are not certainly using
int, they might be using a more efficient data type.This might be for legacy reasons or it might be intentional because it might actually matter a lot. If I make up an example,
chat_participant_idis definitely stored with each message and probably also in some index, so you can search the messages. Multiply this over all chats on WhatsApp, even the ones with only two people in, and the difference betweenu8andu16might matter a lot.But I understand how a TypeScript or Java dev could think that the difference between 1 and 4 bytes is negligible.
Shots fired.
All these tough guys think you can’t bit shift in Java, never worked on a project with more than two people. Many such cases.
Fair point, but still better than wasting a nuclear power plant worth of electricity to solve math homework with an LLM
Probably why I said "almost certainly". And I stand by that. We're not talking about
chat_participant_id, we're talking aboutGROUP_CHAT_LIMIT, probably a constant somewhere. And we're talking about a value that would require a 9-bit unsigned int to store it, at a minimum (and therefore at least a 16-bit integer in sizes that actually exist for types). Unless it's 8-bit and interprets a 0 as 256, which is highly unorthodox and would require bespoke coding basically all over instead of a basicnum <= GROUP_CHAT_LIMIT.I think you're just very confused friend, or misunderstanding how binary counting works, because why in the 9 hells would they be using 9 bits (512 possible values) to store 8 bits (256 possible members) of data?
I think you're confusing indexing (0-255) with counting (0-256), and mistakenly including a negation state (counting 0, which would be a null state for the variable) in your conception of the process. Because yes, index 255 is in fact count 256 and 0 would actually be 1. Index = count -1
I'm imagining something like this:
If
GROUP_CHAT_LIMITis 8 bits, this does not work.So add a +1 like you would for any index to count comparison?
I guess I'm failing to see how this doesn't work as long as you properly handle the comparison logic. Maybe you can explain how this doesn't work...
Orrrr they have a u8 chat_participant_id of some kind and a binary data format for message passing. The GROUP_CHAT_LIMIT const may have a bigger data type, but they may very well be trying to conserve 3 bytes per message. Ids can easily start at 0.
150 gigs of bandwidth saved per day doesn't seem like a whole lot at their scale, but if they archive all the metadata, that's over 50 terabytes a year saved on storage - multiplied by how many copies they have of their data. Still not a lot tbh, but if they also conserve data in every other place they can, they could be saving petabytes per year in storage.
Still weird because then they'd have to reuse ids when people leave, otherwise you could join and leave 255 times to disable a group lol