Bitcoin Forum

They all can't be using Bitcoind and it's JSON-RPC API right? Nor should they be pulling a "Mt. Gox" and rolling their own code... (maybe for blockchain though) So just what are they doing to be a service that reliably processes Bitcoin transactions in such high volume and availability? What do all these high-end services do to receive and send their bitcoins?

Nothing wrong with bitcoind (or a cluster of bitcoinds) if you use it properly.  Building updates around the blocknotify and walletnotify callbacks is one option.  Another option is to run bitcoind in no-wallet mode and use raw transactions for everything.  Nobody however runs any service of any significant volume using the bitcoin "accounts".

bitcoind is not ideal for anything with significant volume, even if you build it around blocknotify/walletnotify.

For bitpay/coinbase, they most likely have listening nodes that listen for any transactions to payment addresses (perhaps using a bloom filter for O(1) time), and when they find one they craft a raw transaction to send it into one of their main wallet addresses.

Sorry, but please replace 'most likely' with 'might'.

(I can't edit my posts.)

What happened to your image editor for forum posting ?