How Fast is Hashgraph?

by Apr 18, 2019Hedera Hashgraph

How Fast is Hashgraph

Hedera Hashgraph Speed

Summary: What makes Hashgraph fast is its unique consensus mechanism and its first-in-class virtual voting algorithm that permits immediate feed-forward parallel processing that outperforms all other public networks with regard to speed, scale, security and stability. Gossip about gossip is another feature that speeds the Hedera network beyond any other distributed ledger technology (DLT). The other fact that makes Hashgraph fast is its absence of blockchain structure as a directed acyclic graph (DAG) that can sustain up to 100,000 transactions per second (TPS) in a single shard, which means without scaling. With scaling solutions, such as with sharding, the number of transactions can easily approach millions of TPS, far beyond any decentralized ledger in blockchain.

Blockchain Speed: Blockchain design offers a security solution at the expense of speed and scale. This is due to the overtly synchronized formation of blocks (eg/ every 10 minutes in bitcoin) which bundled transactions in an unordered system based on fees. Blocks that are generated must wait for the total network to allow a randomized leader to arise from the proof-of-work (PoW) consensus that is then gossiped, or broadcasted to all nodes. This bottlenecks the consensus mechanism to a single random node and disallows a parallel processing of orders. The blockchain network is deliberately slowed to allow this consensus process to occur before another set of transactions can occur. Because of this structure in most of PoW blockchain DLTs, achieving any fast speed or global scale is nearly impossible.

Hashgraph Speed: The fundamental breakthrough in the Hedera public network apart from blockchain design is what makes Hashgraph fast by creating a unique data structure called a Hashgraph. This is a form of DAG that is built on a time ordered structure of hashes, or encrypted small files. When a transaction is created in Hedera, the order is digitally signed with signature by a user, sent to a node at random, and then is propagated in the network logarithmically by all receiving nodes. This process takes a few seconds for small actions like cryptocurrency transfers. The transaction has a hash of the previous transaction to place it in temporal order. When a node receives the transaction, it confirms the digital signature, adds a timestamp by metadata and records it in its local DAG, or graph of hashes (a Hashgraph). It is this graph structure that consensus depends and is the critical structure that makes Hashgraph fast and unstoppable compared to all other decentralized systems.hashgraph node transactionHashgraph Consensus: Understanding the role of the Hashgraph is a challenging task but is essential in to context of the gossip and voting mechanisms. In virtual voting, an age old voting algorithm is optimized by allowing a network to vote on consensus with 100% certainty, but does so virtually. If the Hedera public network used actual voting to form consensus, the bandwidth of communication would be flooded with internodal communication to the point that it would overwhelm any modern telecommunications network. With virtual voting, a vote is calculated virtually by simply referencing the locally generated hashgraph, or graph of network transactions made by gossiping. This means that the Hashgraph consensus achieves perfect finality like a real voting method but without using a single extra resource, just the local graph.

Hashgraph Gossip: Gossip about gossip is important in order to make Hedera Hashgraph fast as well by limiting internodal communication as the network learns about new transactions.  A gossip protocol is a common database communication process in order to update all nodes to the common state. In blockchain this occurs by a random leader block producer that wins a PoW contest based on hashing, or encrypted computation, that then sends the block randomly to the network.hashgraph gossipIn Hedera’s public DLT, a transaction is sent randomly to other nodes which then gossip to other nodes unless they have already received it. When the nodes gossip to one another, they update the Hashgraph locally, but also send gossip about gossip, which is a small data set that lets all nodes know how the nodes communicated to each other and when, by timestamp. This elegantly simple metadata addition to the Hashgraph ensures with mathematical certainty that the network is in perfect sync and not at risk of a double spend or reversible transaction. These properties are not achievable to the degree of certainty in any other blockchain or DAG.

Hashgraph Speed: Finally, the defining features of Hashgraph’s algorithm with its gossip-about-gossip, virtual voting and efficiency in use of bandwidth, while still achieving perfect finality on consensus allow it to be the fastest decentralized network to date. By avoiding inefficient blockchain properties of synchronized and serial processing, the consensus in Hedera makes Hashgraph fast and efficient. Transactions occurring in Hashgraph are fast, near 100,000 TPS per shard with amazing throughout. With sharding for global scaling this number can make Hashgraph approach even millions of TPS at full capacity.

There is no other DAG or blockchain that can achieve these speeds, with bitcoin nearly at 7 TPS, ethereum at 15 TPS, ripple at 1-2k TPS and the Visa network at 2-3k TPS. In order for worldwide adoption of DLT a network would have to be as fast, fair and secure as Hashgraph.

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