4 ms·

Facebook users generally don't intend to transact though.

carbocation 13y ago
Especially not in a way where the exact order of each transaction is critical, so there is no opportunity for any parallelism.
- anonymoushn 13y ago
  So while this is an astute observation, a properly run exchange would go through a lot of effort to separate the matching engine (the inherently single-threaded part of the exchange) from the portions of the system that accept orders and spew data. The registration system and web site also don't belong anywhere they could possibly contend with the matching engine. Real exchanges process orders of magnitude more volume on a single symbol than mtgox does, yet have latencies measured in microseconds rather than tens of minutes.
  - krunaldo 13y ago
    The matching engine should be separated completely from the rest of system as this is the one component where you want to align with cpu cache and all other kind of crazy low level optimizations. I do agree that mtgox system is slow but we should keep in mind the resource difference both in time and money the large stock exchanges have had time to build their systems. Most of the stock exchanges also don't build their own system but rely on buying one from a independent organization or another stock exchange. A small nitpick: Volume is one metric but it does not matter in reality the important part is the amount of transactions on a specific symbol.
    - anonymoushn 13y ago
      A small nitpick: Volume is one metric but it does not matter in reality the important part is the amount of transactions on a specific symbol. That's quite right, thanks :) Real venues incentivize participants to post orders in round lots (generally 100 shares) and some of them penalize participants who add liquidity with extraordinarily low fill rates. These rules help reduce load on the matching engine, and afaik mtgox has no analogous rules.
melvinmt 13y ago
All the more impressive.

Especially not in a way where the exact order of each transaction is critical, so there is no opportunity for any parallelism.

anonymoushn 13y ago
So while this is an astute observation, a properly run exchange would go through a lot of effort to separate the matching engine (the inherently single-threaded part of the exchange) from the portions of the system that accept orders and spew data. The registration system and web site also don't belong anywhere they could possibly contend with the matching engine. Real exchanges process orders of magnitude more volume on a single symbol than mtgox does, yet have latencies measured in microseconds rather than tens of minutes.
- krunaldo 13y ago
  The matching engine should be separated completely from the rest of system as this is the one component where you want to align with cpu cache and all other kind of crazy low level optimizations. I do agree that mtgox system is slow but we should keep in mind the resource difference both in time and money the large stock exchanges have had time to build their systems. Most of the stock exchanges also don't build their own system but rely on buying one from a independent organization or another stock exchange. A small nitpick: Volume is one metric but it does not matter in reality the important part is the amount of transactions on a specific symbol.
  - anonymoushn 13y ago
    A small nitpick: Volume is one metric but it does not matter in reality the important part is the amount of transactions on a specific symbol. That's quite right, thanks :) Real venues incentivize participants to post orders in round lots (generally 100 shares) and some of them penalize participants who add liquidity with extraordinarily low fill rates. These rules help reduce load on the matching engine, and afaik mtgox has no analogous rules.

melvinmt 13y ago

All the more impressive.