Can the bitcoin network keep up with increased number of bitcoin transactions? This question inspired CoinWallet.eu and they came up with initiative which was interpreted as a hacker attack at first and turned out to be a stress test of bitcoin network.
The idea was to deluge the network with bitcoin transactions in order to see if current size of block of data is enough. As a reminder nowadays maximum size is 1 megabyte.
The team conducting the test aimed at proving that 1 mb blocksize endangers bitcoin in case of hacker attack. What did they do? They just simulated such an attack when the system got overloaded with transactions. If the situation happened for real, it would lead to a plenty of unconfirmed transactions and system failure for hours if not for days.
Peter Todd explains the whole process: “CoinWallet.eu claimed they would spend 20BTC – about $5kUSD – to create transactions with a fee of 0.1mBTC/KB. That works out to 200MB worth of transactions, which will take some time to be mined.”
Usacryptocoins.com describes the whole process and results of the test: “It appears the test started at 4 am eastern time, with the size of block 362002 jumping to near the 1 mb blocksize limit. After this point most blocks were near or at the limit, but there were several blocks of normal size, probably since they were mined faster than the spam could fill them up. Starting with block 362030 at 8:21 am nearly every block was at its size limit, with unconfirmed transactions piling up and slowing down transaction speed worldwide. Transaction fees began to rapidly rise as seen in the below chart, exceeding 0.005 Bitcoins per transaction briefly which is 5000% higher than usual. This increase in transaction fees is a direct result of demand to send transactions exceeding the available transaction slots in a block, a beautiful example of the law of supply and demand at work.”
The experiment didn’t go as smoothly as if buttered. At 5 p.m. servers crashed. Although they were soon restarted, production of the planned transaction volume was already impossible. Only 15% of expected volume occurred.
It should be noted that the average number of bitcoin transactions, although growing consistently, does not exceed the limit now. But the test shows that it’s risky to wait until it will. Technically the process of changing a block size is not difficult. The only thing to do is to rewrite a bitcoin code. But the change should be approved by most of miners. Otherwise there would be two different versions of bitcoin running.
Due to crash of servers during the recent test CoinWallet.eu is planning to conduct another one in a week.