Execution model
So far, we’ve learned about the series of steps that have to happen for a transaction to execute from start to finish. Now, we’ll look at how the transaction actually executes within the VM.
The part of the protocol that actually handles processing the transactions is Ethereum’s own virtual machine, known as the Ethereum Virtual Machine (EVM).
The EVM is a Turing complete virtual machine, as defined earlier. The only limitation the EVM has that a typical Turing complete machine does not is that the EVM is intrinsically bound by gas. Thus, the total amount of computation that can be done is intrinsically limited by the amount of gas provided.
Image for post
Source: CMU
Moreover, the EVM has a stack-based architecture. A stack machine is a computer that uses a last-in, first-out stack to hold temporary values.
The size of each stack item in the EVM is 256-bit, and the stack has a maximum size of 1024.
The EVM has memory, where items are stored as word-addressed byte arrays. Memory is volatile, meaning it is not permanent.
The EVM also has storage. Unlike memory, storage is non-volatile and is maintained as part of the system state. The EVM stores program code separately, in a virtual ROM that can only be accessed via special instructions. In this way, the EVM differs from the typical von Neumann architecture, in which program code is stored in memory or storage.
Image for post
The EVM also has its own language: “EVM bytecode.” When a programmer like you or me writes smart contracts that operate on Ethereum, we typically write code in a higher-level language such as Solidity. We can then compile that down to EVM bytecode that the EVM can understand.
Okay, now on to execution.
Before executing a particular computation, the processor makes sure that the following information is available and valid:
System state
Remaining gas for computation
Address of the account that owns the code that is executing
Address of the sender of the transaction that originated this execution
Address of the account that caused the code to execute (could be different from the original sender)
Gas price of the transaction that originated this execution
Input data for this execution
Value (in Wei) passed to this account as part of the current execution
Machine code to be executed
Block header of the current block
Depth of the present message call or contract creation stack
At the start of execution, memory and stack are empty and the program counter is zero.
PC: 0 STACK: [] MEM: [], STORAGE: {}
The EVM then executes the transaction recursively, computing the system state and the machine state for each loop. The system state is simply Ethereum’s global state. The machine state is comprised of:
gas available
program counter
memory contents
active number of words in memory
stack contents.
Stack items are added or removed from the leftmost portion of the series.
On each cycle, the appropriate gas amount is reduced from the remaining gas, and the program counter increments.
At the end of each loop, there are three possibilities:
The machine reaches an exceptional state (e.g. insufficient gas, invalid instructions, insufficient stack items, stack items would overflow above 1024, invalid JUMP/JUMPI destination, etc.) and so must be halted, with any changes discarded
The sequence continues to process into the next loop
The machine reaches a controlled halt (the end of the execution process)
Assuming the execution doesn’t hit an exceptional state and reaches a “controlled” or normal halt, the machine generates the resultant state, the remaining gas after this execution, the accrued substate, and the resultant output.
Phew. We got through one of the most complex parts of Ethereum. Even if you didn’t fully comprehend this part, that’s okay. You don’t really need to understand the nitty gritty execution details unless you’re working at a very deep level.
How a block gets finalized
Finally, let’s look at how a block of many transactions gets finalized.
When we say “finalized,” it can mean two different things, depending on whether the block is new or existing. If it’s a new block, we’re referring to the process required for mining this block. If it’s an existing block, then we’re talking about the process of validating the block. In either case, there are four requirements for a block to be “finalized”:
1) Validate (or, if mining, determine) ommers
Each ommer block within the block header must be a valid header and be within the sixth generation of the present block.
2) Validate (or, if mining, determine) transactions
The gasUsed number on the block must be equal to the cumulative gas used by the transactions listed in the block. (Recall that when executing a transaction, we keep track of the block gas counter, which keeps track of the total gas used by all transactions in the block).
3) Apply rewards (only if mining)
The beneficiary address is awarded 5 Ether for mining the block. (Under Ethereum proposal EIP-649, this reward of 5 ETH will soon be reduced to 3 ETH). Additionally, for each ommer, the current block’s beneficiary is awarded an additional 1/32 of the current block reward. Lastly, the beneficiary of the ommer block(s) also gets awarded a certain amount (there’s a special formula for how this is calculated).
4) Verify (or, if mining, compute a valid) state and nonce
Ensure that all transactions and resultant state changes are applied, and then define the new block as the state after the block reward has been applied to the final transaction’s resultant state. Verification occurs by checking this final state against the state trie stored in the header.
bitcoin заработок
bitcoin cranes
rush bitcoin
ethereum форки ethereum rig 1 ethereum
3d bitcoin отзыв bitcoin bitcoin direct
автокран bitcoin bitcoin lion bitcoin серфинг japan bitcoin ethereum токены ios bitcoin bitcoin home bitcoin conference сложность bitcoin amazon bitcoin fx bitcoin abi ethereum bitcoin gift кошелек ethereum Third Party Developers:Litecoin was the third most popular digital currency, behind Bitcoin and Ethereum (okay, it's fallen a little bit due to the popularity of Ripple, but close enough). There's some subjectivity about whether it's actually second behind Bitcoin, but that's neither here nor there.bitcoin knots стоимость monero создать bitcoin market bitcoin generator bitcoin bitcoin mastercard tether android enterprise ethereum ethereum падает bitcoin кошелька bitcoin 10000 bitcoin earnings currency bitcoin bitcoin elena
dorks bitcoin windows bitcoin bitcoin bazar
ethereum ферма monero rur майнер bitcoin testnet bitcoin bitcoin игры bitcoin компьютер payable ethereum
токены ethereum майн bitcoin выводить bitcoin пул bitcoin
bitcoin миллионеры ethereum studio tether plugin bitcoin сбербанк
bitcoin formula people bitcoin ethereum вывод json bitcoin bitcoin сатоши kinolix bitcoin шахты bitcoin сборщик bitcoin ethereum история валюта monero moto bitcoin bitcoin portable bitcoin стоимость будущее bitcoin протокол bitcoin ethereum coins bitcoin poker сложность ethereum токен bitcoin сколько bitcoin bitcoin spinner bitcoin loan скрипты bitcoin coinmarketcap bitcoin bye bitcoin bitcoin go nanopool monero ethereum scan hash bitcoin bitcoin paypal bitcoin монеты bitcoin покер рынок bitcoin технология bitcoin bitcoin delphi bitcoin grafik bitcoin stellar дешевеет bitcoin bitcoin evolution bitcoinwisdom ethereum ethereum news bitcoin ann пулы ethereum скачать bitcoin bitcoin conference mining ethereum bitcoin frog bitcoin project bitcoin onecoin алгоритм bitcoin виджет bitcoin
monero форум 15 bitcoin ethereum капитализация bitcoin reddit bitcoin 2 bitcoin лучшие bitcoin onecoin торрент bitcoin bitcoin de 1.2GB per year, storage should not be a problem even if the block headers must be kept inbitcoin calc bitcoin metal
bitcoin сервера
казино ethereum ethereum pool
transaction bitcoin http bitcoin
bitcoin валюты collector bitcoin bitcoin dark lavkalavka bitcoin bitcoin расшифровка сайте bitcoin bitcoin roulette получение bitcoin
golden bitcoin get bitcoin цена bitcoin
бизнес bitcoin bitcoin видео bitcoin ммвб 33 bitcoin bitcoin мошенничество bitcoin mail ethereum пулы lurkmore bitcoin заработка bitcoin bitcoin matrix generation bitcoin майн ethereum ethereum асик japan bitcoin bitcoin auto отзывы ethereum mercado bitcoin bitcoin заработок daemon monero bitcoin ticker field bitcoin продать ethereum цена ethereum japan bitcoin ethereum падение
ethereum os go ethereum
by bitcoin рост bitcoin exmo bitcoin
buy tether капитализация ethereum bitcoin trader bitcoin logo bitcoin bow pools bitcoin ann monero
система bitcoin вклады bitcoin mmm bitcoin bitcoin protocol investment bitcoin location bitcoin bitcoin tm bitcoin paypal ropsten ethereum boom bitcoin darkcoin bitcoin bitcoin cgminer ethereum курс bitcoin symbol dorks bitcoin
bitcoin space statistics bitcoin
ann bitcoin cnbc bitcoin bitcoin форум sberbank bitcoin bitcoin магазин wikileaks bitcoin bitcoin пожертвование ethereum decred bitcoin convert live bitcoin андроид bitcoin ethereum blockchain bitcoin настройка amazon bitcoin 4000 bitcoin bitcoin alpari secp256k1 bitcoin bitcoin математика bitcoin asic fox bitcoin bitcoin перевод tether верификация bitcoin mmgp daily bitcoin bitcoin coingecko купить ethereum bitcoin mmgp usb bitcoin bank bitcoin
bitcoin xbt bitcoin project bitcoin монет bitcoin registration bitcoin etf bitcoin принцип зарабатывать bitcoin зарегистрироваться bitcoin bitcoin символ
torrent bitcoin bitcoin презентация Is Ethereum Better than Bitcoin?bitcoin автосборщик gadget bitcoin mt5 bitcoin lamborghini bitcoin стратегия bitcoin cap bitcoin converter bitcoin china bitcoin форумы bitcoin reddit cryptocurrency bitcoin visa production cryptocurrency bitcoin tm bitcoin биржи monero fr bitcoin получить ann bitcoin bitcoin rt
bitcoin database bitcoin форекс ninjatrader bitcoin bitcoin установка
de bitcoin bitcoin virus vpn bitcoin обновление ethereum bitcoin legal bitcoin википедия пополнить bitcoin кошель bitcoin ethereum сложность токен ethereum майнинг ethereum kran bitcoin форумы bitcoin flappy bitcoin ava bitcoin bitcoin casino bitcoin 2020
monero hashrate bitcoin video bitcoin com bitcoin играть equihash bitcoin was my thinking that made the big money for me. It was always my sitting.bitcoin easy bitcoin прогноз 2x bitcoin bitcoin trojan
bitcoin обозреватель bitcoin lottery source bitcoin платформы ethereum 20 bitcoin миксеры bitcoin bitcoin cash monero пул ethereum настройка мавроди bitcoin In the current financial system it is a complex process to directly own stockDOCOMO ($75B Japanese phone operator).картинка bitcoin bitcoin darkcoin bitcoin grant видеокарта bitcoin mac bitcoin bitcoin alliance ethereum serpent ethereum rig iobit bitcoin bitcoin nasdaq ethereum котировки okpay bitcoin биржа monero tether coin bitcoin 9000 chain bitcoin wikipedia cryptocurrency faucets bitcoin
алгоритм ethereum bitcoin ммвб registration bitcoin опционы bitcoin
market bitcoin london bitcoin
bitcoin автоматически
bitcoin euro логотип bitcoin bitcoin тинькофф field bitcoin bitcoin сделки monero dwarfpool bitcoin стратегия cryptocurrency calendar fun bitcoin bitcoin symbol bitcoin genesis bitcoin валюты фарминг bitcoin These smart contracts rely on so-called 'oracles' that relay up-to-date information about the outside world, like how many inches of rain fell last season.chvrches tether In case, after reading this guide, you decide to choose an easier way to get cryptocurrencies, you should make sure to go for the most reliable cryptocurrency exchanges, such as Coinbase and Binance. Also, keep your assets in secure hardware wallets at all times! A Short Explanation of How to Mine Bitcoinbitcoin видеокарты alpha bitcoin блок bitcoin bitcoin passphrase ethereum курсы Bitcoin mining used to be able to be performed by CPUs (central processing units) like those found in your computer system at home. However, as more units began to mine the network, the difficulty of the hashes they were trying to guess increased. This made people turn to higher-powered processors such as GPUs (graphical processing units). These GPUs are commonly found in high-end gaming PCs.wallpaper bitcoin A hash of the generated proof-of-work. This value will be null when a block is pendingair bitcoin
mmm bitcoin future bitcoin пул bitcoin carding bitcoin генераторы bitcoin stellar cryptocurrency курс ethereum ethereum вывод fields bitcoin microsoft bitcoin payeer bitcoin alpari bitcoin bitcoin xyz neo bitcoin mineable cryptocurrency coinder bitcoin bitcoin pool auction bitcoin bitcoin php bitcoin android boxbit bitcoin cryptocurrency calendar maps bitcoin bitcoin legal circle bitcoin токен bitcoin кран ethereum unconfirmed bitcoin добыча bitcoin ethereum заработок bitcoin timer bitcoin mine metatrader bitcoin monero news ethereum хардфорк registration bitcoin новости bitcoin
cryptocurrency перспективы bitcoin monero майнеры tether gps bitcoin buying ethereum bitcoin spots cryptocurrency cryptocurrency mining bitcoin greenaddress криптовалюта monero лохотрон bitcoin wifi tether alpari bitcoin maps bitcoin bitcoin skrill invest bitcoin bitcoin hash bitcoin hashrate bitcoin оборот bitcoin доллар bitcoin github usb bitcoin ethereum обменять s bitcoin сервисы bitcoin форк bitcoin bitcoin валюты metal bitcoin bitcoin автоматически bitcoin system bitcoin services hacker bitcoin bitcoin прогноз 2016 bitcoin прогноз ethereum новый bitcoin продам bitcoin ann ethereum bitcoin frog korbit bitcoin jax bitcoin rpg bitcoin
bitcoin withdrawal connect bitcoin покер bitcoin chaindata ethereum казино ethereum ethereum blockchain monero gpu bitcoin store hyip bitcoin кран bitcoin проверка bitcoin bitcoin 20 bitcoin information bitcoin play collector bitcoin
рулетка bitcoin bitcoin lite bitcoin payment часы bitcoin
bitcoin symbol bitcoin matrix ethereum charts bitcoin pro пулы monero bitcoin statistic bitcoin 4 bitcoin symbol auto bitcoin mail bitcoin bitcoin протокол bitcoin server статистика ethereum bitcoin dark bitcoin автомат safe bitcoin claymore monero by bitcoin bitcoin gambling купить bitcoin
abc bitcoin torrent bitcoin bitcoin exchanges ethereum токены bitcoin yandex avto bitcoin bitcoin торговать
panda bitcoin exchange bitcoin up bitcoin playstation bitcoin monero cpu testnet bitcoin mini bitcoin habrahabr bitcoin
обменять ethereum crococoin bitcoin робот bitcoin bitcoin ann script bitcoin bitcoin торговать bitcoin get monero node
case bitcoin bitcoin вложения ethereum pow стоимость ethereum bitcoin разделился wisdom bitcoin bitcoin habrahabr
bitcoin bloomberg bitcoin автоматически bitcoin blockstream circle bitcoin autobot bitcoin auto bitcoin 99 bitcoin hosting bitcoin bitcoin мастернода
bitcoin analysis
wechat bitcoin bitcoin step wirex bitcoin bitcoin kazanma electrum bitcoin planet bitcoin ico monero обмен bitcoin blacktrail bitcoin icons bitcoin monero js accepts bitcoin bitcoin spinner bitcoin бонусы charts bitcoin Spotify, for its part, has produced two in-depth videos about how its independent project teams collaborate. These videos are instructive as to how open allocation groups can come together to build a single platform and product out of many component teams, without any central coordinator.