Bidl

Abstract

A permissioned blockchain framework typically runs an efficient Byzantine consensus protocol and is attractive to deploy fast trading applications among a large number of mutually untrusted participants (e.g., companies). Unfortunately, all existing permissioned blockchain frameworks adopt sequential workflows for invoking the consensus protocol and executing applications' transactions, making the performance of these applications much lower than deploying them in traditional systems (e.g., in-datacenter stock exchange). We propose Bidl, the first permissioned blockchain framework highly optimized for datacenter networks. We leverage the network ordering in such networks to create a shepherded parallel workflow, which carries a sequencer to parallelize the consensus protocol and transaction execution speculatively. However, the presence of malicious participants (e.g., a malicious sequencer) can easily perturb the parallel workflow to greatly degrade Bidl's performance. To achieve stable high performance, Bidl efficiently shepherds all participants by detecting their misbehaviors, and performs denylist-based view changes to replace or deny malicious participants. Compared with three fast permissioned blockchain frameworks, Bidl's parallel workflow reduces applications' latency by up to 72.7% and improves their throughput by up to 4.3x in the presence of malicious participants. Bidl is suitable to be integrated with traditional stock exchange systems. Bidl's code is released on github.com/hku-systems/bidl.