An Empirical Study of Speculative Concurrency in Ethereum Smart Contracts

Authors Vikram Saraph, Maurice Herlihy

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Author Details

Vikram Saraph
  • Department of Computer Science, Brown University, USA
Maurice Herlihy
  • Department of Computer Science, Brown University, USA

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Vikram Saraph and Maurice Herlihy. An Empirical Study of Speculative Concurrency in Ethereum Smart Contracts. In International Conference on Blockchain Economics, Security and Protocols (Tokenomics 2019). Open Access Series in Informatics (OASIcs), Volume 71, pp. 4:1-4:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


We use historical data to estimate the potential benefit of speculative techniques for executing Ethereum smart contracts in parallel. We replay transaction traces of sampled blocks from the Ethereum blockchain over time, using a simple speculative execution engine. In this engine, miners attempt to execute all transactions in a block in parallel, rolling back those that cause data conflicts. Aborted transactions are then executed sequentially. Validators execute the same schedule as miners. We find that our speculative technique yields estimated speed-ups starting at about 8-fold in 2016, declining to about 2-fold at the end of 2017, where speed-up is measured using either gas costs or instruction counts. We also observe that a small set of contracts are responsible for many data conflicts resulting from speculative concurrent execution.

Subject Classification

ACM Subject Classification
  • Computing methodologies → Parallel computing methodologies
  • Blockchains
  • Smart Contracts


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