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Bitcoin Blockchain Forked By Backward-Compatibility Issue
New submitter jhantin writes "The Bitcoin blockchain has forked due to a lurking backward-compatibility issue: versions older than 0.8 do not properly handle blocks larger than about 500k, and Slush's pool mined a 974k block today. The problem is that not all mining operations are on 0.8; blocks are being generated by a mix of several different versions of the daemon, each making its own decision as to which of the two forks is preferable to extend, and older versions refuse to honor or extend from a block of this size. The consensus on #bitcoin-dev is damage control: miners need to mine on pre-0.8 code so the backward-compatible fork will outgrow and thus dominate the compatibility-breaking one; merchants need to stop accepting transactions until the network re-converges on the backward-compatible fork of the chain; and average users can ignore the warning that they are out of sync and need to upgrade."
Turns out there's an approximately 512K limit to atomic updates in Berkeley DB which were used by versions prior to 0.8. 0.8 uses a new database, allowing blockchains that old versions won't accept to be created.
Is that you Peter? :) I don't know anyone else who would describe the system like that.
Bitcoin is not an O(n^2) network. The total work done by the core nodes is "number of nodes multipled by number of transactions" - that is two very different quantities. It doesn't help the argument to abuse formal notation like that.
Pieter reported today that his optimized secp256k1 implementation can reach 20,000 signature checks per second on a single core. That is a lot better than the generic OpenSSL code was able to manage. Bear in mind that although it sounds scary, all of VISA is only about 10,000 transactions per second. So even if we're generous about our assumptions on number of inputs, CPU load would barely stress a single core. Today. With existing hardware. Disk IO will be the bottleneck for the forseeable future, but we're talking about a working set of a few hundred megabytes today. Even with an order of magnitude growth the entire thing fits in RAM on my puny laptop. And with two orders of magnitude growth it still fits on a pretty average dedicated server.
But Bitcoin will not reach VISA traffic loads today, or this year, or even this decade. By the time it does, dedicating one single computer to being a node will seem a completely trivial investment in order to have full security on the worlds financial system, because let's face it, if Bitcoin is processing tens of thousands of transactions per second then it's well on its way to being exactly that.
Ultimately, Bitcoin is growing fast and will scale up. That is what Satoshi wanted it to be, that is what most of the people actually creating businesses and writing lots of code also want - so if you think that'll make your coins worthless in a few years, I will happily buy them off you.
-Mike Hearn